From smitten kitchen blog. These look wonderful. The blog stated they were good without frosting as a breakfast muffin, just cut the sugar back a bit and sub wheat flour for the cake flour. Also suggested adding pecans to the batter if you like.
Preheat the oven to 350°F Line 28 muffin cups with paper liners.
Sift together the flour, baking powder, baking soda, salt and nutmeg and set aside. Cream the butter and sugars together, beating until fluffy. Add the eggs, one at a time, scraping down the sides and bottom of the bowl between each addition, and then the vanilla. Gently mix in the buttermilk. Stir in the dry ingredients and fold in the peach chunks.
Divide the batter evenly among the prepared cupcake liners. Bake for 18 to 22 minutes, or until a tester inserted into the center of cupcakes comes out clean. Cool the cupcakes for five minutes in the tin, then turn them out onto a wire rack to cool completely.
In a small bowl, whisk together the brown sugar, cornstarch and powdered sugar. In a large bowl, beat the cream cheese and butter until fluffy. Add the sugar-cornstarch mixture and vanilla, beat until frosting is smooth and light. Chill the bowl in the refrigerator until it thickens back up a bit, about 30 minutes, then spread or dollop on cooled cupcakes.