1Cream butter, 3/4 cup sugar and vanilla. Add 3 eggs and beat well. Combine flour, baking powder and soda. Add dry ingredients to butter mixture, alternately with sour cream.
2Combine pumpkin, beaten egg, a half-cup sugar and pie spice.
3Spoon half the batter into 9x13 inch pan. Sprinkle half the streusel over the batter. Spread pumpkin mixture over streusel. Spread rest of batter over the pumpkin mixture. Sprinkle remaining streusel over top.