Blackberry Bottom Cake

Happy belated birthday to me! This year for my birthday two of my friends gave me cooking and baking books... hehe I guess they know me very well! :) This recipe was the first I have tried from my William's Sonoma Savoring Desserts baking book, and it was a great way to start off, especially with beautifully ripe summer fruit like blackberries now available!

Blackberry Bottom Cake
1/3 cup butter, unsalted, melted, and cooled
2 cups sugar
1 pint blackberries
1 cup flour
1 tsp baking powder
1/4 tsp salt

Preheat the oven to 350 F. Melt the butter, and add 1 cup sugar, stirring to combine. Spread this butter/sugar mixture on the bottom of a 9 or 10 inch round baking pan (a springform pan works well) and add the blackberries in a single layer on the butter/sugar mixture. Separate the eggs, putting the whites in a large bowl and the yolks in a smaller one. Whisk 1 tblsp melted butter into the yolks and set aside. Using an electric mixer, beat the egg whites just until the form peaks, being careful not to overbeat. Fold the remaining one cup of sugar into the egg whites, about 1/4 at a time. Then fold in the egg yolk mixture about 1/4 at a time. Final fold in the flour mixture 1/4 cup at a time. Pour the batter over the berries and spread to cover evenly. Bake at 350 F until a toothpick comes out of the center cleanly, approximately 30 minutes. Let stand for at least 10 minutes, at which time slide a knife along the inside edge and then invert over a plate and flip the cake out. Best served warm. Enjoy!