Preheat the oven to 350F. Prepare a 12-cup cupcake tin with liners.
In a large mixing bowl or the bowl of a stand mixed fitted with the paddle attachment, cream together the butter and sugars until fluffy, about 3-4 minutes. Add in the sour cream and vanilla extract and mix until well combined. Add in the egg whites the mix until well combined. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
In a separate bowl, whisk together flour, baking powder, salt, and cinnamon. Add the dry ingredients to the batter from step two and mix until well combined. Add in the milk and bourbon then mix until well combined. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
Fill the cupcake liners about 1/2 to 3/4s full of the batter. Bake for 14-16 minutes or until a toothpick inserted comes out clean. Remove cupcakes from oven and allow to cool for 2-3 minutes, then transfer to a cooling rack to finish cooling.
Make the frosting while the cupcakes are cooling: Add butter to a large mixing bowl or the bowl of a stand mixed fitted with the paddle attachment then cream/whisk until smooth, about 2-3 minutes. Add 3-4 tablespoons of caramel sauce and the vanilla extract mix until well combined. Add in the powdered sugar and mix until smooth and well combined. Add additional caramel sauce as needed to get desired consistency.
Frost your cupcakes using either a piping bag or another frosting tool (I used a piping bag fitted with Wilton's 1M piping tip). Drizzle with additional caramel sauce as desired.