Preheat oven to 350 degrees and line a muffin pan with cupcake liners, set aside. Mix together all ingredients for the cupcakes until combined. Scrape bowl and mix one minute more until batter is smooth.
Divide batter evenly into prepared cupcake liners, filling each liner about 3/4 full. Bake cupcakes 17-20 minutes or until a toothpick inserted in the center comes out clean. Cool completely on a wire rack.
To make the filling, in a small saucepan, combine chopped peaches, brown sugar, vanilla and cinnamon. Heat over medium high and bring to a boil. Reduce heat to low and simmer 4-5 minutes until thickened. Transfer filling to a small bowl and cool mixture to room temperature.
Once the cupcakes have cooled, use a paring knife to cut a circle out of the center, cutting 2/3 of the way to the bottom. Fill the hole with peach filling, repeat with all cupcakes.
To make the frosting, in a small bowl, blend the butter with an electric hand mixer then add the finely chopped peaches and dry frosting mix. Blend until smooth and creamy. Place frosting in a piping bag with a star piping tip and twist the end closed. Pipe frosting onto each cupcake and garnish with a slice of peach.