Preheat oven to 350℉ and grease the bottom and sides of a springform pan with cooking spray.
Melt the butter and pour it into the pan; spread to an even layer.
1/4 cup salted butter
Sprinkle with sugar and then top with the blueberries. Spread the berries to an even layer; set aside.
1/2 cup sugar, 2 cups blueberries*
In a small bowl, combine the flour, baking powder, baking soda and salt; set aside.
1 1/2 cups flour, 1 teaspoon baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon salt
In the bowl of a stand mixer, cream the butter and sugar until light and fluffy.
1/4 cup salted butter, 3/4 cup sugar
Add the egg, sour cream and vanilla and mix until well-combined.
1 egg, 1/2 cup sour cream, 1 teaspoon vanilla
Add the dry ingredients and mix.
Slowly pour the milk into the batter and mix until just combined.
1/3 cup milk
Pour into the pan over the blueberries and spread to an even layer.
Bake for 20 minutes, then cover with aluminum foil (you'll want to tent it – don't cover too tightly).
Bake an additional 20-30 minutes or until a toothpick in the center comes out clean.
Let cool for 10 minutes, then run a butter knife around the edge of the pie pan and flip over onto a serving platter.
Enjoy warm or room temperature with a dollop of whipped cream, if desired!