Preheat the oven to 350°F (176°C) and prepare a cupcake pan with cupcake liners.
In a large mixing bowl, whip together the butter and sugars together until light in color and fluffy, about 3-4 minutes. Do not skimp on the amount of mixing time.
Add sour cream and vanilla extract and mix until well combined.
Add egg whites in two batches, mixing until well combined after each. 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. Set aside.
In a small measuring cup, combine the milk and bourbon. Set aside.
Add half of the dry ingredients to the batter and mix until well combined. Add the bourbon mixture and mix until well combined. Add remaining dry ingredients and 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 halfway. Bake for 14-16 minutes, or until a toothpick inserted comes out with a few crumbs.
Remove cupcakes from oven and allow to cool for 2-3 minutes, then remove to cooling rack to finish cooling.
To make the frosting, add the butter to a large mixer bowl and mix until smooth.
Add about half of the powdered sugar and mix until smooth and well combined.
Add 3-4 tablespoons of caramel sauce and the vanilla bean paste to the frosting and mix until well combined.
Add the remaining powdered sugar and mix until smooth.
Add additional caramel sauce as needed to get desired consistency.
Pipe the frosting onto the cupcakes using a large open star tip. Drizzle with additional caramel sauce as desired.