Preheat oven to 350 degrees. Butter and flour an 8 or 9 inch square cake pan

In the bowl of a mixer with a paddle attachment combine the cinnamon, flour, sugar, brown sugar and butter on a low speed until blended and mixture starts to form clumps. Reserve 1 cup of the crumb topping for later to top off the cake.

Add baking powder, baking soda and salt to the flour mixture.  Whisk together the sour cream, egg, and vanilla until blended. Add this liquid mixture to the remaining flour mixture and mix until smooth. Spread it into the prepared cake pan. Sprinkle the peaches and blueberries over the batter and then the reserved crumb topping over the fruit.

Bake for about 40 minutes until firm to the touch in the middle and toothpick inserted into the cake comes out clean.

Cool on a wire rack.

Sprinkle with powdered sugar and cut into squares to serve.