Make sure all your ingredients are room temperature.
In a separate bowl, combine flour, salt, cinnamon, baking powder and soda and mix.
Using your mixer fitted with the paddle attachment or a handheld electric beater, blend butter, sugar, vanilla and bourbon at medium speed until pale and fluffy.
Add eggs, one at a time, scraping the bowl after each addition.
Reduce speed to low and add a cup of flour followed by ⅓ of the buttermilk.
Repeat this 3 times, until you have incorporated all the flour and buttermilk.
Fold in diced peaches.
Fill cups with cupcake batter ⅔ full and gently tap on counter to remove air bubbles.
Streusel Topping
In a bowl, combine sugars, cinnamon, and melted butter.
Stir in the flour.
Top each cupcake with 1 teaspoon of streusel topping.
Bake cupcakes for 15-17 minutes or until toothpick is inserted and comes out clean. Allow to cool completely before frosting.
Frosting-
Using an electric mixer, beat together all ingredients except the milk.
Add the milk, 1 tablespoon at a time until you reach frosting consistency.