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!