Plum, Streusel Coffee Cake

1. Preheat oven to 400 F.
2. Grease an 8 x 8 x 2 inch square pan. Set it aside.
3. Prepare the streusel topping in a medium bowl. Mix together the ½ cup Bisquick, oats, brown sugar, cinnamon and nutmeg.
4. Cut the cold butter into that mixture, using a pastry blender (cutter), two knives, or your hands. Blend until the mixture is crumbly.
5. Stir in the nuts, and set aside.
6. In a large bowl mix the 2 cups of Bisquick and the granulated sugar.
7. Make a well in the center of the dry ingredients; and add into that well the milk, egg and vanilla. Mix until smooth. A few small lumps are okay.
8. Pour half of the cake batter into the greased pan.
9. Top with the diced plums.
10. Top the plums with half of the streusel topping.
11. Pour the rest of the cake batter over that.
12. Sprinkle the remaining streusel on the top.
13. Bake 25 to 35 minutes. Remove cake from the oven and let it cool at least 20 minutes before serving. Can be served warm or at room temperature.