Step 1

For the cookies: Position an oven rack in the center of the oven and preheat to 350 degrees F.

Step 2

Beat the cream cheese, butter and confectioners' sugar together in a large mixing bowl with a handheld mixer until light and fluffy, 2 to 3 minutes. Scrape down the bowl. Add the egg, vanilla and lemon zest and beat until smooth, another minute. Scrape down the bowl again. Add the almond and coconut flours and the salt. Beat until a slightly sticky dough forms. Halve the dough and shape each into a flat disc. Wrap each in plastic and chill in the freezer until firm, about 30 minutes.

Step 3

Work with one disc of chilled dough at a time, leaving the other in the freezer. Place the dough between 2 sheets of parchment paper and roll to 1/4-inch thickness. Carefully peel off the top sheet of parchment. Dip a 3-inch round cookie cutter into some coconut flour to help keep it from sticking to the dough and cut the dough into rounds. (The dough is very soft, so you will likely have to leave the cookies in place and scrape away the surrounding dough.) If you like, use mini cookie cutters to cut a hole from the middles of the rounds for half of the rounds. The dough will probably be too soft to transfer the cookies, so slide the parchment paper with the rounds onto a baking sheet. Gather the scraps of dough together and flatten into another round. Wrap the disc of dough in plastic, and chill in the freezer. Place the baking sheet of cut cookies into the freezer to chill for 10 to 15 minutes. Meanwhile, repeat the process with the second disc of chilled dough. Reroll the scraps and cut out more cookies. (You should be able to cut a total of 18 to 20 rounds.)

Step 4

Bake one sheet of cookies at a time for 5 minutes. Turn the oven down to 300 degrees F and continue to bake, rotating the pan halfway through, until lightly golden on the edges, about another 10 minutes. Transfer the baking sheet to a rack. (Do not try to transfer the cookies from the baking sheet until completely cooled.) Increase the oven to 350 degrees F and repeat with the other cookies.

Step 5

For the frosting: With a handheld mixer, beat the butter in a bowl until light and airy. Add the confectioners' sugar, vanilla and salt. Mix on low speed until smooth. Transfer a third of the frosting to a piping bag and set aside. Divide the remaining frosting evenly between 2 bowls. Add about 1/2 teaspoon red gel paste to one bowl and 1/2 teaspoon green gel paste to the other. Mix until the color is evenly distributed, adding more gel as desired. Transfer to two more piping bags. Cut off the tips of the bags when ready to assemble.

Step 6

To assemble: Pair off the cookie rounds into tops and bottoms, using any cookies with cutouts as tops. Arrange the flat sides of the bottom cookies facing up. Pipe about 3 tablespoons frosting onto the bottom cookies. Smooth the frosting with an offset spatula. Top with the flat sides of the top cookies facing down, pressing gently so that the frosting is pushed to the edges of the cookies.

Step 7

Put the crushed peppermint candy and sprinkles on separate plates. Place the sanding "sugar" in a bowl. Roll the edges of each cookie in the candy or sprinkles, or spoon the sugar over the frosting. Sprinkle any cut-out windows with more decorations as desired.