Cake:

3/4 c. granulated sugar
1/2 c. (1 stick) butter
2 large eggs
1 tsp. vanilla
1 1/4 c. all-purpose flour
1 tsp. baking powder
1/2 tsp. salt
3/4 lb. plums (4 to 5 medium plums)
confectioners sugar (for sifting over cake)

Preheat oven to 350°F. Butter and flour 9-inch round or square baking pan at least 2-inches deep.

Beat sugar and butter until fluffy. Add eggs and vanilla. Beat after each addition. Sift in flour with baking powder and beat until just combined. Spread cake batter in pan, smoothing top. Arrange fruit over it. Sprinkle Streusel (recipe below) over fruit and bake 1 hour.

Streusel:

1 c. sugar
1/2 c. firmly packed light brown sugar
1/2 c. or more walnuts
3/4 stick (6 tbsp.) unsalted butter, cut into pieces and softened
1 tsp. cinnamon
1/4 tsp. freshly grated nutmeg
1/2 tsp. ginger

Pulse together in processor until crumbly.