Preheat oven to 350 degrees F. Grease an 8-inch spring form pan, or 8-inch baking pan. (Square or circle).
To make the crumb topping, add the flour, brown sugar, cinnamon and pinch of salt into a medium bowl. Stir together. Add the butter and cut into the flour mixture with a pastry cutter or fork until the butter is broken down into small pieces. Place in the refrigerator until ready to add to the coffee cake.
In a medium bowl, combine the flour, salt, baking powder and baking soda. Whisk together.
In a separate large mixing bowl, add the sugar, eggs, Greek yogurt, milk, oil, and vanilla extract. Whisk together until fully combined.
Add the dry ingredients into the wet. Stir until just combined. Pour the batter into the spring form pan, and gently level out with a knife or spatula.
Starting on the outside of the pan, start placing the peach slices over the batter, slightly overlapping each slice. Once the outside of the pan is competed, fill in the center, again making sure to overlap slightly.
Evenly spread the blueberries over the peaches. Get the crumb topping from the fridge and sprinkle over the blueberries and peaches.
Bake for 35-40 minutes or until the batter is just set. Let cool slightly and enjoy!