Preheat oven to 400 degrees F. Line a standard cupcake pans with 10-12 liners and set aside.
In a medium bowl, whisk together flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer, cream butter and sugar 3 minutes until light and fluffy. Add eggs and vanilla, mixing until blended well.
Add the milk/horchata and flour mixture in alternate additions, beginning and ending with flour. Mix until just combined - don't overmix.
Fill the cupcake liners 3/4 of the way full, and bake for 5 minutes at 400 degrees, then reduce heat to 350 and bake an additional 10-12 minutes, until a toothpick inserted in the center comes out clean.
Remove from oven and allow to cool in pan for 5 minutes, then move to cooling rack. When cool, use a cupcake corer or small knife to make a well in the center of each cupcake.
While cupcakes are baking, make buttercream. In a KitchenAid stand mixer fitted with a whip attachment (or with a hand mixer), add butter and sift 2 cups of powdered sugar over it. Beat on low to combine, then increase speed to high for 3-4 minutes to blend.
Add vanilla, Horchata, Fireball, and salt, and blend on low until incorporated. Taste and add 1-2 more cups powdered sugar as necessary to reach desired flavor and consistency.
Once incorporated, increase speed to high and whip for 3-4 minutes until fluffy.
Spoon into a piping bag and fill each cooled cupcake with frosting, then top with desired amount.
Garnish with dragee sprinkles and cinnamon sugar. Serve and enjoy!
Amount Per Serving
Calories409kcalCalories from fat 164
% Daily Value
Percent Daily Values are based on a 2,000 calorie diet. Your daily values may be higher or lower depending on your calorie needs: