This is a single-pan protein cake made from blended oats, egg whites, and vanilla protein powder, with a cinnamon layer swirled through the middle. It takes 17 minutes start to finish, and the part that matters most is blending the batter until it’s fully smooth — leftover oat texture is what makes these turn out gummy instead of cake-like.
Quick facts
| Prep time | 5 minutes |
|---|---|
| Cook time | 12 minutes |
| Total time | 17 minutes |
| Servings | 2 |
| Difficulty | Easy |
Why this version works
Blending the oats fully into the batter, instead of leaving them coarse, is what gives this a cake-like crumb instead of a gummy one. Layering half the batter, then cinnamon, then the rest, and only lightly swirling with a knife keeps the cinnamon as a defined ripple instead of blending it into the whole cake. A small 4.5-inch pan matters too — a wider pan spreads the batter too thin and it cooks dry before the center sets.
Ingredients
- ½ cup oats
- ¼ cup (4 tbsp) liquid egg whites (about 2 large egg whites)
- ⅔ cup water
- 2 scoops vanilla protein powder (about 2 oz)
- 1 tsp stevia
- 1 tsp baking powder
- 1 tbsp cinnamon
Substitutions
- Sweetener: swap stevia for monk fruit sweetener or regular sugar, same amount.
- Protein powder: chocolate protein powder works for a mocha-style version instead of vanilla.
- Oats: quick oats or rolled oats both blend smooth — no need for one over the other.
- Gluten-free: use certified gluten-free oats to keep this recipe gluten-free.
How to make cinnamon swirl protein cake
- Preheat. Set your oven to 390°F (200°C) and let it fully heat before you start mixing — a cold oven throws off the bake time.
- Blend the batter. Combine oats, egg whites, water, protein powder, stevia, and baking powder in a blender. Blend until completely smooth, with no visible oat pieces left — this is what keeps the texture cake-like instead of gummy.
- Layer the base. Pour half the batter into a small 4.5-inch nonstick pan. Sprinkle the cinnamon evenly over this layer.
- Top and swirl. Pour the remaining batter over the cinnamon. Drag a knife through the batter a few times to create a marbled swirl — a few strokes is enough, more than that blends the cinnamon in completely and you lose the ripple.
- Bake. Bake 12 minutes, then check with a toothpick inserted in the center — it should come out clean or with a few moist crumbs, not wet batter. Add 1–2 minutes if it’s not there yet.
- Rest and slice. Let the cake cool in the pan for at least 5 minutes before removing and slicing — cutting into it too early makes it fall apart.
Pro tips
- Use a small nonstick pan so the cake releases cleanly without tearing.
- If the cake doesn’t rise well, try a different brand of protein powder — some contain additives that flatten the rise.
- A few knife strokes are enough for the swirl; more than that mixes the cinnamon in completely.
- A light spray of oil in the pan helps release even with a nonstick surface.
Common mistakes
- Gummy texture — almost always from underblending, leaving oat pieces in the batter instead of a smooth mix.
- Cake doesn’t rise — check your baking powder is fresh, or try a different protein powder brand.
- Swirl disappears entirely — too many knife strokes blend the cinnamon layer into the batter instead of marbling it.
- Cake falls apart when sliced — it needs the full 5-minute rest in the pan before you cut into it.
Storage and reheating
Store in an airtight container in the fridge for 3–4 days. Reheat a slice in the microwave for about 30 seconds to bring back the fresh-baked texture.
Nutrition (per serving, approximate)
| Calories | ~180 |
|---|---|
| Protein | ~24g |
| Carbs | ~13g |
| Fat | ~3g |
Exact numbers vary by protein powder brand — check the label on yours for the most accurate count.
Quick answers
Can I use a different protein powder flavor?
Yes, chocolate protein powder works well and gives it a mocha-style flavor.
Is this gluten-free?
Yes, as long as you use certified gluten-free oats.
Can I bake this in a larger pan?
Not well — this recipe is sized for a 4.5-inch pan. A larger pan spreads the batter thin and it dries out before the center sets.
Do I need to grease the pan?
Yes, even with a nonstick pan, a light spray of oil helps it release cleanly.
Why is 2 egg whites listed as 4 tablespoons instead of 6?
2 large egg whites measure closer to 4 tablespoons (about 2 oz). If your batter feels too thick, don’t add extra egg white to make up a 6-tablespoon amount — add a splash of water instead.
Can I double this recipe?
Yes, but bake it in two separate 4.5-inch pans rather than one larger pan, or the center won’t cook through in the same time. For another quick, protein-forward breakfast, the protein waffles scale up easily too.
Serving suggestions
- Top with a dollop of Greek yogurt for extra creaminess.
- Add fresh blueberries or raspberries for color and a bit of tartness.
- Drizzle a small amount of almond butter over the top.
- Serve with a hot cup of coffee or tea.
A few more high-protein treats to try
If you liked the warm cinnamon flavor here, the cinnamon apple breakfast quinoa leans on the same spice in a completely different format. For a make-ahead protein dessert, the protein cheesecake jars are worth trying next. Want something you can batch and keep on hand? The cottage cheese protein cookies store well for a few days. And for another single-serving breakfast bake, the cottage cheese breakfast rounds come together just as fast.
The first time I made this, I only pulsed the blender a few times and the finished cake had a slightly gritty, oat-heavy bite instead of a smooth crumb. Now I blend it until it’s genuinely smooth, almost like a thin pancake batter, and the texture comes out right every time.
Cinnamon Swirl Protein Cake
This is a single-pan protein cake made from blended oats, egg whites, and vanilla protein powder, with a cinnamon layer swirled through the middle. It takes 17 minutes start to finish, and the part that matters most is blending the…
- ½ cup oats
- ¼ cup (4 tbsp) liquid egg whites (about 2 large egg whites)
- ⅔ cup water
- 2 scoops vanilla protein powder (about 2 oz)
- 1 tsp stevia
- 1 tsp baking powder
- 1 tbsp cinnamon
- Sweetener: swap stevia for monk fruit sweetener or regular sugar, same amount.
- Protein powder: chocolate protein powder works for a mocha-style version instead of vanilla.
- Oats: quick oats or rolled oats both blend smooth — no need for one over the other.
- Gluten-free: use certified gluten-free oats to keep this recipe gluten-free.
- Preheat. Set your oven to 390°F (200°C) and let it fully heat before you start mixing — a cold oven throws off the bake time.
- Blend the batter. Combine oats, egg whites, water, protein powder, stevia, and baking powder in a blender. Blend until completely smooth, with no visible oat pieces left — this is what keeps the texture cake-like instead of gummy.
- Layer the base. Pour half the batter into a small 4.5-inch nonstick pan. Sprinkle the cinnamon evenly over this layer.
- Top and swirl. Pour the remaining batter over the cinnamon. Drag a knife through the batter a few times to create a marbled swirl — a few strokes is enough, more than that blends the cinnamon in completely and you lose the ripple.
- Bake. Bake 12 minutes, then check with a toothpick inserted in the center — it should come out clean or with a few moist crumbs, not wet batter. Add 1–2 minutes if it's not there yet.
- Rest and slice. Let the cake cool in the pan for at least 5 minutes before removing and slicing — cutting into it too early makes it fall apart.
- Use a small nonstick pan so the cake releases cleanly without tearing.
- If the cake doesn't rise well, try a different brand of protein powder — some contain additives that flatten the rise.
- A few knife strokes are enough for the swirl; more than that mixes the cinnamon in completely.
- A light spray of oil in the pan helps release even with a nonstick surface.
Bella is a home cook who turns simple, everyday ingredients into meals worth gathering around. On Finds Your Recipe she shares quick weeknight dinners, cozy comfort food, and easy desserts made for real, busy life — no fancy skills needed, just good food on the table.
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