Preheat oven to 350° F. Prepare a 12 count muffin pan by spraying with baking spray.
Place 1/2 tablespoon butter and 1 teaspoon brown sugar in the bottom of each muffin cup. Next add 2-3 raspberries and 2-3 slices of peaches.
Make the cake by creaming together remaining 1/2 cup softened butter and sugar together for 3-5 minutes using a hand or stand mixer. Add in egg and vanilla then combine well.
In a separate bowl, combine flour, baking powder, cinnamon and salt. Add the flour mixture and buttermilk alternately to batter. Mix until just combined. Using a large scoop (or about 1/4 cup), add cake batter to each muffin cup.
Place muffin pan on top of a baking sheet (in case of spillage) then place in the oven. Bake for 25-30 minutes or until toothpick inserted into cake comes out clean.
Let cool for 5-10 minutes then run a knife around the edges. Place a wire rack over the muffin pan then carefully turn the pan upside down to remove the cakes. Place wire rack with cakes on top of the baking sheet to catch juices and glaze.
To make glaze, whisk confectioners sugar, milk, and vanilla in a small bowl then drizzle over cooled cakes.
Notes
You can skip the glaze and serve the cakes warm with your favorite vanilla ice cream.