Mix the topping ingredients together with fork or hands until crumbly. Set aside.
COFFEE CAKE
Preheat the oven to 325°F. Spray a 9x13-inch pan with nonstick spray.
Use an electric mixer to cream together the butter, sugar and vanilla in a large bowl; add eggs and beat well.
In a separate bowl, whisk together flour, baking powder, and baking soda. Mix dry ingredients into the butter mixture half at a time, alternating with half of the sour cream.
In another bowl, combine the pumpkin puree, egg, ⅓ cup sugar, and pie spice. Keep separate.
Spoon half of the batter mixture into the prepared pan. Sprinkle half of the streusel topping over the batter. Spread the pumpkin mixture over the streusel. Carefully spread the remaining batter over the pumpkin mixture. Sprinkle remaining streusel on top.
Bake 45 to 50 minutes, or until toothpick inserted in center comes out clean.