Keto Vanilla Birthday Cake

Name: Keto Vanilla Birthday Cake
Prep time: 15 min
Cook time: 20 min
Yield: 16
Cuisine: American
Ingredients: 2 cups almond flour; 2 tablespoons oat fiber; 1/4 cup unflavored whey protein isolate; 1 tablespoon baking powder; 1/2 teaspoon salt; 6 egg whites, room temperature; 1/2 cup unsalted butter, melted; 1/3 cup plain Greek yogurt or sour cream; 1 cup sugar-free sweetener; 1 tablespoon vanilla extract; 1/4 cup unsweetened nut or seed milk; 2 cups unsalted butter, softened room temperature; 1 1/2 cups powdered sugar-free sweetener; 1 1/2 tablespoons vanilla extract; 1/4 cup heavy cream

by KetoFocus.com

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This keto birthday cake is everything a celebration cake should be—fluffy, moist, and spongy with rich vanilla flavor and creamy vanilla buttercream. No dry, gritty, dense texture here—just the perfect gluten-free, low carb cake that tastes like the real deal thanks to a few game-changing ingredients.

Side view of a slice of keto white cake showing the moist crumb and thick layer of frosting, topped with a single pink candle.

Frosted keto vanilla birthday cake decorated with piped buttercream swirls on the edges.

A bright and colorful view of a slice of keto vanilla cake with a pink candle and piped frosting on top.

Two slices of keto white birthday cake on plates, each topped with a brightly colored candle.

35 Mins

Nutrition Facts

Serving Size:
1 slice

Servings

372

Calories

36.6g

Fat

6.5g

Protein

1.7g

Net Carb

33.2g

Total Carbs

If you’ve been on the hunt for a keto birthday cake that actually tastes like cake—not cornbread, not a brick, not something you politely choke down in front of your low-carb friends—this is it. This keto white cake has the soft, fluffy crumb and sweet vanilla flavor you’d expect from a classic celebration cake, plus a dreamy vanilla buttercream frosting that you’ll want to eat with a spoon. I’ll be honest, my chocolate keto cake usually steals the show around here, but after serving this at a family birthday party, even my chocolate lovers were converted. It’s light, spongy, and doesn’t scream “I’m on a diet,” which is exactly what a birthday cake should be.

What sets this cake apart from all the other almond flour-based keto cakes out there? The secret’s in the texture—and trust me, that matters more than anything when you’re trying to recreate a traditional cake experience. Most low carb cakes end up dense, dry, or worse… greasy. I wanted this one to have bounce. Soft, cloud-like bounce. So I brought in two MVP ingredients: oat fiber and whey protein isolate. Oat fiber adds that zero-carb, delicate fluff factor (it’s the insoluble part of oat husks, not actual oats), and whey protein gives the cake structure and lift, making it feel light instead of heavy.

It took a few test rounds and a couple tragic cake fails, but this final version is everything I wanted in a vanilla keto cake. It’s naturally gluten-free, has just the right amount of sweetness, and doesn’t rely on coconut flour or a dozen eggs to get the job done.

Why this keto white cake is worth baking

Actually fluffy. Like boxed cake mix fluffy. No weird dense texture or dry crumb.
No coconut flavor or gritty mouthfeel. I skip the coconut flour and lean into almond flour, oat fiber, and protein powder for a smoother bite.
Zero weird aftertaste. I use sweeteners that don’t overpower the vanilla flavor.
Perfect for non-keto eaters. No one will know it’s low carb…unless you tell them.
Customizable. Use it as a base for cupcakes, layer cakes, or even a wedding cake (yes, really).

So go ahead, stick some candles in it. This one deserves a celebration!

Table of Contents [ click to toggle ]

Recipe Details
- Keto Vanilla Birthday Cake Ingredients
- Keto Vanilla Birthday Cake Directions
Similar recipes others love
Troubleshooting Common Keto Cake Mistakes
Storage information
FAQs
Nutrition information: facts & macronutrients

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Keto White Cake Ingredients

2 cups almond flour
2 tablespoons oat fiber
1/4 cup unflavored whey protein isolate
1 tablespoon baking powder
1/2 teaspoon salt
6 egg whites, room temperature
1/2 cup unsalted butter, melted
1/3 cup plain Greek yogurt or sour cream
1 cup sugar-free sweetener
1 tablespoon vanilla extract
1/4 cup unsweetened nut or seed milk

Double Batch Keto Vanilla Buttercream Frosting Ingredients

2 cups unsalted butter, softened room temperature
1 1/2 cups powdered sugar-free sweetener
1 1/2 tablespoons vanilla extract
1/4 cup heavy cream

Keto Vanilla Birthday Cake Directions

STEP

1

Preheat oven & prepare cake pans

Preheat oven to 350°F. Line two 8-inch round cake pans with parchment and lightly grease the sides with butter. Set aside.
STEP

2
Mix dry ingredients

In a large bowl, whisk together almond flour, oat fiber, whey protein powder, baking powder, and salt. Set aside.
Ingredients

2 cups almond flour

2 tablespoons oat fiber

1/4 cup protein powder

1 tablespoon baking powder

1/2 teaspoon salt
STEP

3
Beat egg whites

In another large bowl, whisk the egg whites until slightly frothy, about 2 minutes.
Ingredients

6 egg whites, room temperature
STEP

4
Add remaining wet ingredients

To the egg whites, add melted butter, yogurt, sugar-free sweetener, vanilla, and milk of choice.
Ingredients

1/2 cup unsalted butter, melted

1/3 cup plain Greek yogurt or sour cream

1 cup sugar-free sweetener

1 tablespoon vanilla extract

1/4 cup milk of choice
STEP

5

Finish cake batter

While mixing with an electric mixer, pour the ingredients into the dry ingredients and stir until just combined.

Quick Tip
Batter should be thick but spreadable—add a splash more milk if too dry.
STEP

6

Bake the cake

Divide evenly between pans and smooth the tops. Bake at 350°F for 20–25 minutes, or until tops are set and a toothpick comes out clean. Let cool in pans 10 min, then transfer to wire racks.
STEP

7
Make the buttercream frosting

In a large, clean bowl, beat the softened butter with an electric mixer until pale and fluffy (about 4-5 minutes). Add sweetener and beat until combined. Mix in vanilla, then gradually add heavy cream until desired consistency is reached. Frost cooled cake layers.
Ingredients

2 cups unsalted butter, softened

1 1/2 cups powdered sugar-free sweetener

1 1/2 tablespoons vanilla extract

1/4 cup heavy cream

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Troubleshooting Common Keto Cake Mistakes

Let’s be real, keto cakes have a bit of a reputation. If you’ve ever bitten into a low carb cake that tasted like eggs, collapsed into a pancake, or had the texture of a sponge that’s been left in the sink too long… you are not alone. But don’t worry. I’ve made all those mistakes for you so you don’t have to. Here’s how to avoid the most common keto cake flops:

Why is my cake dense and rubbery?

Most likely culprit? Too much moisture and not enough structure. Traditional flour gives baked goods a built-in fluff factor that almond flour just doesn’t have. That’s why this recipe uses whey protein isolate and oat fiber—they balance the fat-heavy almond flour and give the cake a proper crumb.
Fix: Don’t swap out the protein powder or oat fiber unless you really know what you’re doing. And don’t overmix the batter—it can make the cake tight and chewy instead of fluffy.

Why does it taste eggy?

Keto recipes love to throw a dozen eggs into everything, and it shows. That strong egg flavor happens when you’re using whole eggs without enough other ingredients to balance them out.
Fix: This recipe uses just the egg whites, which keeps the structure without adding yolk-heavy flavor. Stick with it unless you’re okay with a yellow, slightly richer cake.

Why is my cake greasy or wet on the bottom?

Too much fat or not enough absorbent ingredients (like oat fiber) can cause the cake to settle and separate, especially after cooling.
Fix: Make sure you’re measuring your butter correctly—melted, but not hot—and don’t sub out the oat fiber. It’s not just filler; it’s magic.

Why did my cake fall in the center?

A sunken cake usually means it wasn’t fully baked or cooled too quickly.
Fix: Make sure your oven is fully preheated and don’t open the oven door until at least 20 minutes in. Let the cake cool in the pan for a bit before removing—it helps it set.

Why is my frosting sliding off the cake?

If you try to frost a cake while it’s still warm, you’re basically inviting a meltdown—literally.
Fix: Let the cake cool completely (and I mean room-temp, no cheating), and if your buttercream is too soft, chill it in the fridge for 5–10 minutes before spreading.

Keto baking isn’t hard. It just plays by different rules. And once you know what not to do, it’s a whole lot easier to bake cakes that actually taste like cake.

Storage information

Once your cake is fully frosted (or even unfrosted), you can store it in the fridge for up to 5 days. Just make sure it’s covered, either in an airtight container or loosely wrapped with plastic wrap, so it doesn’t dry out or absorb that mysterious fridge smell we all pretend not to notice.

If you want to make it ahead or save leftovers for later, this cake also freezes beautifully. Wrap individual slices or full layers tightly in plastic wrap, then again in foil or a freezer bag, and freeze for up to 2 months.

To thaw, just pop it in the fridge overnight or let it sit at room temperature for about 30–60 minutes. The texture stays soft, the crumb stays fluffy, and no one would ever guess it came out of the freezer.

Keto Vanilla Birthday Cake: FAQS

Can I use whole eggs instead of egg whites?

Technically, yes, but using whole eggs will give the cake a yellow tint and may change the texture slightly. If you want that classic white cake color and a lighter crumb, stick with egg whites.

What kind of protein powder should I use?

I recommend unflavored whey protein isolate. It blends well and helps fluff up the cake. Avoid casein or plant-based protein powders they absorb liquid differently and can make the cake gummy or dense.

Can I use collagen powder in place of protein powder?

Unfortunately, no. Collagen powder doesn't substitute well with protein powder in keto baked goods and cakes.

Can I substitute something else for oat fiber?

Oat fiber is a bit of a unicorn in this recipe. It helps create that light, spongy texture. You could try using coconut flour in its place but the flavor and texture may be slightly different.

Can I make this into cupcakes?

Absolutely. Divide the batter evenly into cupcake liners and bake at 350°F for about 18–20 minutes, or until the tops are set and a toothpick comes out clean.

Can I eat this cake for breakfast?

Look, I’m not here to tell you how to live your life. It’s made with protein powder, so technically it’s basically a macro-friendly breakfast… with frosting. Just call it a "vanilla breakfast loaf" if anyone asks.

Nutritional information & Macros

Amount Per Serving
Calories	372
Fat	36.6g
Protein	6.5g
Total Carbs	33.2g
Net Carbs	1.7g

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