High-Protein British Coffee Cake (Reduced Sugar, Coffee-Forward)

A British-style coffee cake where coffee flavour is the main design variable, not an afterthought.
Sugar is partially replaced with erythritol and sucralose, and protein is increased using whey while preserving a classic, tender crumb.
Designed for excellent flavour first, improved nutritional profile, and reliable results when stored in the refrigerator.

• ⏲️ Prep time: ~35 min
• 🍳 Cook time: ~25 min
• 🍽️ Servings: 10 slices

Ingredients

Coffee Sponge (2 layers)

• 170 g plain flour
• 45 g whey protein isolate (unflavoured)
• 25 g chocolate whey protein (MyProtein Brownie Chocolate)
• 170 g unsalted butter, softened
• 110 g caster sugar
• 60 g erythritol (powdered)
• Sucralose equivalent to ~60 g sugar
• 4 egg yolks (≈ 72 g)
• 4 egg whites (≈ 130 g)
• 90 g espresso (~8–10% TDS), cooled
  or 90 g very strong brewed coffee (Aeropress or moka preferred), optionally supplemented with 4–5 g instant coffee
• 14 g baking powder
• 6 g glycerol monostearate (GMS)
• 4 g salt

Coffee Protein Cream (Swiss-style, coffee-forward)

• 120 g egg whites
• 35 g erythritol (powdered)
• Sucralose equivalent to ~70 g sugar
• 3 g salt
• 140 g unsalted butter, softened
• 60 g chocolate whey protein (MyProtein Brownie Chocolate)
• 40 g strong brewed coffee, cooled
  or 1 double espresso (~28 g)

Directions

Coffee Sponge

1. Cream butter, caster sugar, erythritol, and sucralose on high speed for 5–6 minutes until pale and aerated.
2. Add egg yolks one at a time, mixing fully after each addition.
3. Mix in baking powder and GMS until evenly dispersed.
4. With mixer on low, add half the coffee liquid, then half the dry ingredients; mix just to combine.
5. Add remaining coffee liquid and dry ingredients; mix only until homogeneous.
6. In a clean bowl, whisk egg whites with salt to stiff peaks.
7. Fold the meringue into the batter in three additions, gently preserving volume.
8. Divide batter evenly between prepared tins (see Portioning & Storage for volumes).
9. Bake at 175–180 °C for 22–26 minutes, until internal temperature reaches 96 °C.
10. Cool completely before frosting.

Coffee Protein Cream

1. Combine egg whites, erythritol, sucralose, and salt in a heatproof bowl.
2. Heat over simmering water, stirring continuously, until mixture reaches 85 °C.
3. Transfer to mixer and whip on high until stiff, glossy, and cooled to ~32 °C.
4. With mixer running, add butter 1 tbsp at a time, fully emulsifying.
5. Whisk brewed coffee or espresso with the chocolate whey to form a smooth paste.
6. Add this coffee–protein mixture gradually and whip until fully incorporated and smooth.

Assembly

1. Spread a thin, even layer of coffee protein cream over the first sponge.
2. Place the second sponge on top and frost lightly.
3. Keep frosting restrained so the coffee sponge remains the dominant flavour.

Portioning & Storage

Per portion (plated):

• 1 slice (~130 g finished cake)

Batter yield and volume

• Total raw batter mass: ~960 g
• Approximate batter volume (after folding): ~1.3–1.4 L

Per layer (2 layers):

• Mass: ~480 g
• Volume: ~650–700 mL

Recommended cake tins

Round tins (2 layers):

• 20 cm (8 in) diameter × 4–5 cm height — ideal thickness and even bake
• 18 cm (7 in) diameter acceptable — slightly taller layers; add ~2–3 min bake time

Square tins (single layer):

• 20 × 20 cm (8 × 8 in): bake 30–35 min
• 23 × 23 cm (9 × 9 in): bake 22–25 min

Storage

• Refrigerator: 3–4 days, covered
• Best served cool or after 20–30 min at room temperature

Nutritional Information (Approximate)

(1 portion = 1 slice, ~130 g finished cake)
Assumed cooked yield: ~1,300 g total

Sodium assumption: ~4 g salt total across recipe.
1 g salt ≈ 393 mg sodium.

Notes

• Espresso is the reference standard for coffee intensity; brewed coffee may be used, but non-pressurised methods require either acceptance of lower intensity or supplementation with a small amount of instant coffee.
• Chocolate whey is biased toward the cream to avoid cocoa-driven dryness in the sponge.
• GMS improves emulsification and crumb softness, compensating for reduced sugar and added protein.
• Coffee flavour is present in both sponge and cream and should read clearly even when the cake is served cold.
• This recipe is optimised for refrigerated storage, not freezing.