Prepare a large baking pan by lining it with parchment paper. Sift together your almond flour and powdered sugar in a bowl, and set it aside.

In the bowl of a stand mixer {make sure it's really clean}, add place the egg whites and cream of tartar. Using the whisk attachment, beat until frothy.

Once the mixture has started to become frothy, slowly pour in the granulated sugar in a stream while continuing to beat. The mixture will become more opaque and glossy. Stop just before you've reached "stiff peaks." {Don't overmix.} If you're using vanilla extract or food coloring, this is a good time to add it and give it a quick mix before adding the dry ingredients.

Add about half of your sifted almond flour and sugar mixture to the beaten egg whites and gently fold it in until it has disappeared. Add the remaining almond flour mixture and repeat the process until it is fully incorporated. The mixture should be thick, and "ribbons" of the batter should be visible for a few seconds before it settles into itself when you drizzle it in the bowl.

Scoop the mixture into a piping bag {if you have a small round tip, that works well to help pipe, but is not necessary}. To pipe your macarons, gently squeeze the bag holding it vertically so that the batter pools into a perfectly round 1 ¼ to 1 ½ inch circle. Pipe onto the parchment until you've used up all the batter. {They won't spread too much, but give them an inch or so of space between each one.}

Gently, but firmly tap the pan on the counter top to help get rid of any bubbles. Set the macarons aside and let them air dry for about 30 minutes. You want them to develop a "skin", meaning they won't be wet and sticky anymore when you touch them lightly with your finger. This may take longer depending on the humidity where you live.

This is a good time to preheat the oven to 300 degrees. Once the macarons are "dry", you may put the baking pan in the oven and let them bake for 18-20 minutes. I always like to check just a bit before then to make sure they're not browning. If they are, put another large baking sheet on the rack above to block some of the heat.

Once they are done, remove them from the oven and allow them to cool. If they don't come off the parchment easily at this point, I like to let them cool in the oven with the door slightly cracked to help them dry, then remove them from the oven and cool them completely before trying to move them.

Meanwhile, make your filling. Simply beat the butter and powdered sugar until smooth, then add the Irish Cream a tablespoon at a time until you've reached the desired consistency.

For the Ganache: Place chocolate chips in a small bowl. Heat the heavy cream in a small cup in the microwave until bubbling, about 30-45 seconds. Pour over chocolate chips and let it sit for about a minute, then whisk until smooth. Set aside to cool.

When ready to pipe the filling, scoop the buttercream into one piping bag and the ganache into another. Pipe around the edge of one of the macaron shells with the buttercream, creating an "O" shape -- the ganache will be piped into the hollow portion in the center. Pipe half of the shells with buttercream, then fill with the ganache. Top the piped shell with an unpiped shell to create a "sandwich."

Refrigerate in an airtight container if not serving right away, but bring to room temperature before serving.