Preheat an oven to 350 F. Prepare the blueberry center by combining the frozen blueberries, ½ tbsp all-purpose flour, and 1 tbsp granulated sugar and grated nutmeg.
Combine the dry ingredients for the cake, including the all-purpose flour, poppy seeds, baking soda, and kosher salt. Set aside.
In the bowl of a stand mixer, prepare the lemon cake by combining room temperature butter and sugar with a paddle attachment until light and fluffy, about 3-4 minutes. Add in the egg and beat until combined. Add in the lemon zest and lemon extract and vanilla extract and mix briefly until combined.
Alternate the flour mixture and the sour cream. First, add half of the flour mixture then half of the sour cream. Mix slightly on low speed, and then add the remaining flour and sour cream. Mix until just combined.
Place batter into a 9” springform pan, sprayed with nonstick cooking spray. Spread the batter around evenly with an offset spatula.
Using the offset spatula, make a 3 ½” indent into the center of the cake. The indent will hold the blueberries. Carefully scoop the blueberries into the center of the cake. It will look like a lot of blueberries, but the cake will rise around them.
Bake cake for 50-55 minutes or until the cake is set and cooked. Since the blueberries will be in the center of the cake, you can stick a paring knife into the cake just outside the filling to test for doneness.
While the cake is baking, make the glaze by combining the powdered sugar and lemon juice. Pour this over the hot cake and allow the glaze to sink in before cutting the cake.
Tips
This recipe uses frozen wild blueberries, which are smaller in size. Feel free to use regular-sized blueberries as well.
Using freshly squeezed lemon juice for the glaze makes all the difference in flavor.
Ensure the eggs, butter, and sour cream are room temperature as it helps create a better emulsion and better cake.
