Blueberry Lemon Streusel Cake

This is a wholesome, lightened-up blueberry lemon cake that hits the brunch table without the butter-heavy guilt. The cake skips butter entirely (egg white provides the structure that yolks usually do) and a homemade buttermilk substitute (milk plus lemon juice) gives it the acid that activates the baking powder for fluffy lift. Oats baked into the cake and the streusel topping add fiber and a gentle nutty texture that pair naturally with bursting blueberries and bright lemon.

The technique that makes this work is the milk-and-lemon-juice trick. Letting them sit for a couple minutes curdles the milk into instant buttermilk, and the acidity tenderizes the gluten in the flour and gives the cake its characteristic tangy moistness. Tossing the blueberries in with the dry ingredients (rather than folding them into wet batter) coats them in flour and keeps them suspended through the cake instead of sinking to the bottom. The streusel topping is unconventional, just oats, nutmeg, honey drizzle, and wheat germ, but it crisps into a sweet, crunchy lid.

Pro Tips

• Use fresh or frozen blueberries. Don’t thaw frozen berries first. Frozen berries hold their shape and don’t bleed purple streaks.
• Grate the lemon zest fresh, not bottled. Bottled zest has lost its essential oils and tastes flat.
• Spread the batter to the edges of the pan evenly. Uneven thickness means some pieces cook through before others.
• Cool the cake in the pan for 15 minutes before slicing. Hot cake crumbles, slightly cooled cake slices clean.

Variations

• Substitute raspberries, blackberries, or chopped peaches for the blueberries.
• Use orange juice and orange zest in place of lemon for a different citrus angle.
• Add a half cup of chopped walnuts or pecans to the streusel for crunch.