In the bowl of a stand mixer or in a large bowl with a hand mixer, beat together butter and sugar until light and fluffy, about 3 minutes. Beat in egg yolk and eggnog.
In a separate large bowl, whisk together flour, almond flour, and salt. Add flour mixture to the wet mixture and mix until just combined, taking care not to over-mix.
Divide dough in half and pat each half into a disc. Wrap dough in plastic wrap and place in fridge until firm, about 1 hour
On a lightly floured surface, roll one disc of dough out to be about ¼"-thick (leave second disc of dough in fridge). Cut out cookies with a medium or large cookie cutter and transfer to a parchment paper-lined baking sheet. Be sure to re-roll and dough scraps to cut out as many cookies as you can. Place cookie sheet in fridge for about 30 minutes and take second dough disc out.
On lightly floured surface, roll second dough disk out to be about ¼"-thick and cut shapes with same cookie cutter. Transfer these to a second parchment paper-lined baking sheet and use a smaller cookie cutter (can either be a small version of the large one or something totally different. I did large trees with a small star cut out in the middle) to make a cutout in the center of each. Place this cookie sheet in fridge for 30 minutes to chill.
Preheat the oven to 350°F.
Bake both sheets of cookies for 8 to 10 minutes, or until the edges are just beginning to turn golden. Let them cool for 5 minutes on the pan, before transferring to a wire rack to cool completely.
Optional: Using eggnog icing, drizzle designs over the cookies with the cutouts. Dip in a bowl of sprinkles, icing side-down to decorate.
Place the cookies with the cutouts in them on a cookie sheet and sift confectioners' sugar over the top. Turn the remaining cookies flat side up and spread about ½ teaspoon of eggnog icing into the center. Top with the sugar-dusted cookies.