Blackberries: another recipe

I picked enough blackberries to make just one more dessert. I decided to try to adapt my upside down cake recipe for blackberries and it turned out to be really good so I decided to share.

Blackberry Upside-Down Cake

3 tablespoons butter, melted
1/3 cup sugar
2 1/2 cups blackberries or enough blackberries to cover the bottom of a 9" pan.

Cake:
6 tablespoons butter, softened
1/2 cup sugar
1 large egg
2 teaspoons vanilla extract
1 1/4 cups self-rising flour
1/2 cup buttermilk

Directions
1. Preheat oven to 350 degrees with rack in center. Spray the bottom and sides of an 9-inch round cake pan with cooking spray and add 3 tablespoons melted butter to pan. Pour blackberries into pan and sprinkle 1/3 cup sugar over berries.
2. Pour cake ingredients into a mixing bowl and mix until well combined.
3. Spoon batter over berries in pan, and smooth top. Bake cake until a toothpick inserted in the center comes out clean, 30 to 35 minutes. Let cool on a wire rack for 20 minutes. Run a knife around edge of cake and invert onto a rimmed platter. If blackberry mixture sticks to bottom of pan, just remove from pan with a spatula and smooth onto the top while warm.

Serve with whipped cream or vanilla ice cream.

The only problem is that the blackberries are gone.