Preheat oven to 350 degrees. Line one muffin tin with regular baking cups, tulip baking cups or panettone baking cups, set aside.
In the bowl of a stand mixer, combine butter and sugar. Beat on medium until light and fluffy, about 1 minute. Add egg, mix then egg yolk. Mix in vanilla until just combined.
In a medium size mixing bowl, combine flours, baking soda, salt and cinnamon. Whisk to combine. With mixing speed on low, alternate dry ingredients with sour cream and milk. Mix until the batter is smooth and no flour pockets remain.
To make the cinnamon crumb topping, in a small bowl whisk together flour, sugars and cinnamon. Pour the melted butter over and using your hands, mix until it becomes clumpy.
Scoop 1 tbsp. of batter into the bottom of each muffin cup, spread to cover the entire base. Place a few slices of peaches over. Cover with remaining batter, then top with remaining peaches and the blueberries. Sprinkle the crumb topping over each, gently pressing it down. You will notice that there is a generous amount of topping, you’ll want to use it all!
Place into oven and bake for 25-28 minutes or until a cake tester comes out clean and the tops of the muffins are golden brown. Remove from oven and allow to cool in pan for 5 minutes before transferring to a wire rack to cool completely.