Instructions

1. Preheat the oven to 350 degrees F. Butter and flour a 9-inch round cake pan or spray the pan with non-stick spray and line with parchment paper.
2. Make the streusel: Combine the granulated sugar, brown sugar, cinnamon, and nutmeg in a bowl. Stir in the melted butter and then the flour. Mix well and set aside for later.
3. Make the cake: In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar on high speed for 4 to 5 minutes, until light and fluffy.
4. Reduce the speed to low and add the eggs one at a time. Add the vanilla extract, fresh lemon zest, and sour cream. Mix until just combined.
5. In a separate bowl, sift together the flour, baking powder, baking soda, and salt. With the mixer on low speed, add the flour mixture to the batter until just combined.
6. Fold in the blueberries with a spatula, making sure the batter is completely mixed.
7. Spoon the batter into the prepared pan and spread it out with a knife or an offset spatula.. With your fingers, crumble the streusel topping evenly over the batter. You can also squeeze it together to make large clumps.
8. Bake for 40 to 50 minutes, until a cake tester or a skewer inserted into the center comes out clean.
9. Cool completely on a wire rack, then dust generously with confectioners’ sugar before serving.