Preheat the Oven

Thirty minutes or longer before baking, set oven racks at the middle and lowest levels. Preheat the oven to 375°F/190°C. Place a sheet of heavy-duty aluminum foil on the lower rack to catch any bubbling juices.

Make the Blueberry Filling

In the pie plate, stir together the lemon zest, lemon juice, sugar, cornstarch, and salt. Add the blueberries and toss to coat them.

Mix the Liquid Ingredients

In a medium bowl, whisk the egg yolks, 1 tablespoon of the sour cream, and the vanilla just until lightly combined.

Make the Batter Topping

In the bowl of a stand mixer fitted with the flat beater, mix the flour, sugar, baking powder, baking soda, and salt on low speed for 30 seconds. Add the butter and remaining sour cream. Mix on low speed until the dry ingredients are moistened. Raise the speed to medium and beat for 1½ minutes. Scrape down the sides of the bowl. Starting on medium-low speed, gradually add the egg mixture in two parts, beating on medium speed for 30 seconds after each addition to incorporate the ingredients and strengthen the structure. Scrape down the sides of the bowl.

Using a silicone spatula, drop the batter onto the blueberries, leaving a 1 inch border between the batter and the sides of the pie plate and a 2 inch space in the middle.

Bake the Cake

Bake for 30 to 40 minutes, or until a wire cake tester inserted into the center (just into the cake) comes out clean and the cake springs back when pressed lightly in the center. After 30 minutes, if the top of the cake is browning too much, cover it loosely with aluminum foil that has been lightly coated with nonstick cooking spray.

Cool the Cake

Let the cake cool in the pie plate on a wire rack until barely warm or room temperature. The flavors blend best when no longer hot.