Line baking sheet with a silpat mat or parchment.*
Place the almond powder, icing sugar, and nutmeg in a food processor. Process until just beginning to clump.
Sift and discard any bits that won't pass through the sifter. Set aside.
Whip the egg whites until they're the consistency of a loose foam. Continue whipping while slowly adding sugar. Whip to a stiff meringue.
Fold the dry mixture into the meringue.**
Pour the batter into a piping bag fitted with the 1A tip.
Pipe the macarons onto your baking sheet.
When all your macarons are piped, whack the baking sheet on the counter at least 3 times to get rid of any air bubbles.***
Let the macarons dry at room temperature until dry to the touch. Approx 1 hour. DO NOT skip this step.
While macarons are drying, make the ganache.
Chop the chocolate finely and place in a bowl. Heat the eggnog until boiling and pour over chopped chocolate. Do not stir! Cover bowl with plastic wrap for 2 mins. Stir to emulsify ganache. Place in fridge to set.****
Once dry, bake macarons in a 300°F oven until they stick a little bit to the pans. This can be anywhere from 10-20mins depending on your oven and how crowded the macarons are on the pan.
Let cookies cool completely before removing from pans.
Pipe ganache into the center, sandwich the cookies and twist together.
* I create a parchment template using a 11/2" cookie cutter to create circles and place it under my silpat mat. ** You will need to do a LOT of folds to get the batter to the proper consistency. You're looking for it to be smooth and shiny and have some movement. If you lift some up with a spatula, it should pour in a steady stream and settle into the remaining batter. DO NOT overmix. *** Do not be shy with the whacking! ****If the ganache has some unmelted bits after stirring, heat over a simmering bain marie.