In a small bowl, combine the crumble ingredients (butter, brown sugar, flour and cinnamon). Mix well and set aside.
MAKE THE MUFFINS
In a small bowl, combine the blueberries and 1 tablespoon flour. Mix well and set aside. Preheat oven to 375 degrees F and line a muffin tin with cupcake liners (or spray generously with cooking spray). Using a stand mixer fitted with the paddle attachment (or a large mixing bowl with a hand mixer), combine the butter, brown sugar, sugar, eggs and vanilla and beat until combined.
In a separate bowl, combine the flour, baking powder, baking soda and salt. Mix well. Gradually add to the butter mixture and beat on medium-low speed until just combined. Gently fold in the blueberries and peaches.
Fill the prepared muffins cups completely full of batter. The batter will be thick. Sprinkle the crumbles evenly over the tops. Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the centers comes out clean. Repeat with remaining batter and crumbles. Serve warm!