Preheat oven to 375F. Lightly grease a medium-sized baking dish. Set aside.
In a small bowl combine the streusel ingredients and using your fingers work it into a crumb-like consistency.
Next add the blueberries and peaches to a large bowl and mix in the sugar and vanilla. Pour fruit mixture into the baking dish and sprinkle with the flour. Top the fruit with the streusel, spreading evenly over the top. Bake for 45 minutes, or until bubbly and browned.