What is “streusel”? It’s the German term for a crumbly topping made with flour, butter and sugar to which spices and nuts are sometimes added. In this recipe, the streusel is scattered between the bluberries on top of the cake. The streusel turns crisp during baking to give the cake a top that’s crunchy in spots. The interplay between crunchy streusel and moist blueberries is simply terrific.
Why combine lemon with blueberries? Why not just berries? That was how we baked streusel cake before. With strawberry or blueberry, or both. The lemon was something my daughter, Alex, picked up from culinary school. The lemon juice creates a balance so that the cake is not overly sweet. The lemon zest adds a beautiful aroma to the cake.
This lemon blueberry streusel cake is best served warm. To store any leftover, place in a tightly-covered container and keep in the fridge.
Lemon blueberry streusel cake
- ¾ cup cake flour
- ½ teaspoon baking powder
- ⅛ teaspoon salt
- 10 tablespoons butter - at room temperature
- ½ cup plus 2 tablespoons white sugar
- 1 whole egg - plus one egg yolk
- 3 tablespoons full cream milk
- juice of one lemon
- zest of one lemon
- ½ cup frozen blueberries
For the streusel topping
- ⅓ cup all-purpose flour
- ⅓ cup white sugar
- ¼ teaspoon ground cinnamon
- ¼ cup cold unsalted butter - cut into small cubes
- Preheat the oven to 350F.
- Grease and flour the bottom and sides of an 8-1/2″x4-1/4″ loaf pan (skip the greasing and flouring if using a silicone pan.
- Sift the flour, baking powder and salt into a bowl.
- In a large mixing bowl, beat the butter and sugar until light and fluffy. I used a hand mixer but a wire whisk will do. DO NOT overmix: you will know you have overmixed if the butter solids separate from the fat.
- Add the egg and yolk and mix until fully incorporated.
- Add the flour and milk in batches. Add a third of the flour first, mix; add half of the milk, mix; add the next third of the flour, mix; then the remaining milk and, finally, the rest of the flour.
- Stir in the lemon juice and zest.
- Pour the batter into the prepared pan.
- Make the streusel mixture. Using your fingertips, rub together all the streusel ingredients until the mixture resembles coarse crumbs.
- Scatter the frozen blueberries on top of the cake batter. Fill the gaps with the streusel mixture.
- Bake at 350F (remember to lower the heat if using a dark colored pan) for one hour to one hour and 15 minutes or until a toothpick inserted at the center comes out clean.
- Cool the cake in the pan for about half an hour before inverting and slicing.