A magic custard cake is one of those clever desserts where a single thin batter bakes into two layers on its own: a light sponge on top and a silky custard underneath. Swapping in Simply Desserts Vanilla Protein Pudding mix gives that custard layer real body and a sweet vanilla flavour with no added sugar, plus a protein lift, so each slice lands around 8g protein. Honest heads-up: it is still a baked custard cake with eggs and a little butter, so it is a smarter treat rather than diet food, and the mix is dairy so this is not vegan.
Recipe: Protein Custard Cake
Ingredients
- 1 box Simply Desserts Vanilla Protein Pudding Mix
- 4 large eggs, separated
- 1/2 cup granulated erythritol or monk fruit sweetener
- 4 tablespoons unsalted butter, melted and slightly cooled
- 3/4 cup all-purpose flour
- 2 cups warm milk (dairy gives the silkiest custard)
- 1 teaspoon vanilla extract
- Pinch of salt
Instructions
- Preheat your oven to 325F (160C) and line an 8x8 inch baking pan with parchment paper.
- In a large bowl, whisk the egg yolks with the erythritol until pale, then whisk in the melted butter and vanilla.
- Whisk in the Simply Desserts Vanilla Protein Pudding mix and the flour until smooth.
- Gradually whisk in the warm milk a little at a time until you have a thin, pourable batter. It will look very loose, which is correct.
- In a separate clean bowl, beat the egg whites with a pinch of salt to stiff peaks, then gently fold them into the batter in three additions. Keep it loose, with small flecks of egg white still visible.
- Pour into the lined pan and bake for 40 to 50 minutes, until the top is set and lightly golden and the middle has a gentle wobble.
- Cool completely in the pan, then chill for at least 2 hours so the layers set. Cut into 9 squares: a light sponge on top and a soft custard underneath.
Nutrition Facts
| Nutrient | Per Serving |
|---|---|
| Calories | 160 |
| Protein | 8g |
| Fat | 8g |
| Sugar | 3g |
| Fiber | 1g |
Why This Recipe Works
Magic custard cake works because the batter is deliberately thin and the beaten egg whites are folded in loosely. As it bakes, the heavier custard sinks and sets while the lighter sponge rises to the top, giving you two textures from one bowl. Simply Desserts Vanilla Protein Pudding mix is a natural fit for the custard layer: its milk protein, corn starch and emulsifiers are exactly what thickens a custard, so it sets soft and silky rather than watery, while adding protein and a vanilla sweetness with no added sugar (it is sweetened with erythritol and stevia). The eggs do the structural work and the warm milk carries it all, so the finished cake tastes like a proper custard dessert with more protein and far less sugar than the classic version.
Simply Desserts is a real dessert brand, not a protein supplement company trying to make dessert. That means genuine flavour, creamy texture, and clean ingredients. Each serving delivers about 8g of protein, and the Simply Desserts pudding base stays sugar-free (any sugar comes from your mix-ins).
Variations
Chocolate Custard Cake
Use Simply Desserts Chocolate Protein Pudding mix and add 2 tablespoons of cocoa powder to the batter for a chocolate magic custard cake.
Berry Topped
Once chilled, top each square with fresh raspberries or blueberries for a little tartness against the creamy custard.
Higher-Protein Version
Use ultra-filtered dairy milk in place of regular milk to lift the protein further (Simply Desserts notes the mix can reach 40g+ protein per box with ultra-filtered milk).
Custard and Cake Cups
Bake the batter in a lined muffin tin for individual custard cakes. Reduce the bake time to about 22 to 28 minutes and watch for a set top with a gentle wobble.
Frequently Asked Questions
How do you make a magic custard cake with protein pudding mix?
Whisk 4 egg yolks with 1/2 cup erythritol, then whisk in melted butter, vanilla, 1 box of Simply Desserts Vanilla Protein Pudding mix and 3/4 cup flour. Gradually whisk in 2 cups warm milk, fold in 4 whipped egg whites, then bake in an 8x8 pan at 325F for 40 to 50 minutes. Chill before cutting so the sponge and custard layers set.
How much protein is in this custard cake?
Cut into 9 squares, each slice works out to roughly 8g of protein. The Simply Desserts pudding mix contributes 20g protein per box, and the eggs and milk add the rest. It is more protein than a regular custard cake, given as an honest calculated figure rather than 20g per slice.
Why didn't my custard cake separate into layers?
The two most common reasons are a batter that is too thick or egg whites that were overmixed in. The batter should be very thin and pourable before baking, and the whipped whites should be folded in gently so small flecks remain. Too much mixing blends everything into one even sponge instead of separate layers.
Is this custard cake healthy or sugar-free?
It is low in added sugar, around 3g per slice, because the Simply Desserts mix is sweetened with erythritol and stevia and most of the remaining sugar is the natural lactose from the milk. But it is still a baked dessert with eggs and butter, so it is a lower-sugar, higher-protein treat rather than a diet food.
Is this protein custard cake vegan?
No. It uses eggs, and the Simply Desserts pudding mix is made with milk protein and is certified Kosher Dairy, so the recipe is neither vegan nor dairy-free. The mix contains milk as an allergen.
Try Vanilla Protein Pudding
20g protein per box. Zero sugar. Real dessert flavour. Ready in 2 minutes.
