Separate the eggs, you will be using only the egg whites. Cover the bowl of egg whites and let sit for about an hour to come to room temperature.
Preheat the oven to 350º F. Line a baking sheet with parchment paper.
Sift the almond flour and confectioners' sugar several times and remove any large pieces of almond meal.
Using a mixer with the whisk attachment, on low speed beat the egg whites and granulated sugar for 1 minute to combine.
Increase the speed to high and beat until the egg whites form stiff, glossy peaks.
Add the almond flour and confectioners sugar mixture. Gently fold to combine with a spatula. Use about 40 strokes, the batter should flow like lava.
Pour the macaron batter into a piping bag that has been fitted with a medium round tip (1/2 inch plain tip or 1/3 inch plain tip).
Pipe the batter into 3/4 inch rounds about 1 inch apart.
Tap the baking sheet firmly on the countertop 3-4 times to release air bubbles.
Let the macarons sit on the counter for 20-30 minutes until the tops harden slightly.
Bake at 350º F for about 12 minutes.
Allow to cool completely before filling with the Baileys Buttercream Frosting.
Preparing the Baileys Buttercream Frosting
Using an electric mixer, beat the butter and confectioners' sugar until fluffy.
Add the Baileys Irish Cream, 1 tablespoon at a time until the buttercream is a spreadable consistency, but still firm enough so it does not spread when piped onto the cookie).
After the shells have cooled, spread or pipe the frosting on the underside of a macaron and cover with another macaron.