Directions

1. Line 4 baking sheets with parchment paper (see Note).
2. Combine butter, granulated sugar and brown sugar in the bowl of a stand mixer fitted with the paddle attachment. Cream until light and fluffy, 4 to 5 minutes. Add egg and vanilla extract, and mix on medium speed until well incorporated, scraping down the sides of the bowl to incorporate all the ingredients well.
3. Add flour, baking soda, baking powder, and salt and mix on low speed until combined. Scrape the bowl well, then mix on low speed again until a smooth, homogeneous dough forms.
4. Pour sanding or sparkling sugar in a shallow bowl. Preheat the oven to 350 degrees F (175 degrees C) with the oven racks in the upper and lower thirds of the oven.
5. To create the trees you will need cookies in 3 different sizes. Portion out 22 scoops of dough in each of the following sizes: 1 teaspoon, 2 teaspoons, and 1 tablespoon and set on the prepared baking sheets. Keep same size dough portions together on the same baking sheet and divide the 1 tablespoon cookie dough portions amongst 2 baking sheets.
6. Use your hands to roll each dough portion into a ball, then roll dough balls through the sanding or sparkling sugar to generously coat. Return cookies to the baking sheets, spacing them at least 1 inch apart.
7. Working in batches, transfer baking sheets to the preheated oven. Bake until cookies are lightly golden brown at the very edge, 5 to 7 minutes for the smallest cookies, 6 to 8 minutes for medium-sized cookies, and 7 to 9 minutes for the largest ones. Carefully transfer cookies to wire racks and cool completely.
8. Combine cream cheese and butter in the bowl of a stand mixer fitted with the paddle attachment. Cream until light and fluffy, about 3 minutes. Scrape the bowl well, then add powdered sugar in 3 to 4 additions, mixing well and scraping the bowl after each addition. Add the vanilla, salt, and sour cream and mix on medium speed to combine. Stop the mixer and scrape the bowl well, then mix again on medium speed to make sure everything is evenly combined. Add food coloring and mix until frosting is evenly colored. Add more green food coloring for a deeper color.
9. Fit a pastry bag with a medium star tip (such as Ateco 20, 21, or 22) or medium round tip (such as Ateco 9, 10, or 11). Transfer some of the frosting to the pastry bag, aiming to fill it no more than halfway full.
10. To assemble the cookie stacks place the largest cookies on a parchment lined baking sheet. Hold the pastry bag directly over each cookie and pipe on enough frosting to cover the surface of the cookie, leaving about 1/2 inch uncovered around the outer edge. Repeat with all of the largest cookies. Place a medium cookie on top of each frosted large cookie and press down slightly - the frosting should now come just barely to the outer edge.
11. Frost medium sized cookies the same way you frosted the large cookies, leaving about 1/2 inch uncovered around the outer edges. Set a small cookie on top of each cookie stack, pressing down lightly to spread the frosting just barely to the outer edges.
12. Pipe a tall swirl of frosting on top of each cookie stack, like you would on a cupcake, to create the top of the “tree”. Decorate the exposed frosting with sprinkles and/or more sparkling sugar.
13. Store in an airtight container until ready to serve - the stacks taste best within 5 days of assembling.