In a medium bowl, whisk together the flour, baking powder, and salt, then set the mixture aside.
In a larger mixing bowl (or the bowl of a stand mixer), cream the softened butter and sugar together on medium speed, beating until the mixture is light, fluffy, and pale in color—about 2-3 minutes.
Next, add the eggs and vanilla extract to the creamed butter-sugar mixture. Beat on medium speed until just combined, scraping down the sides of the bowl as needed.
Gradually add the reserved dry ingredients, mixing on low speed until everything comes together and a smooth cookie dough forms—be careful not to over mix.
Add egg and vanilla, mix until just combined. Stir in flour mixture and blend well.
To portion the dough, use three different-sized cookie scoops to form balls in graduated sizes: large (about 1.5 inches wide for the base), medium, and small.
Scoop out sets of one large, one medium, and one small ball for each Christmas tree cookie you’ll assemble.Place the dough balls on baking sheets lined with parchment paper or silicone baking mats, spacing them a few inches apart.
Bake in a preheated 375°F oven for 5-7 minutes, or until the edges are lightly golden and the bottoms are set.
Remove the cookies from the oven and transfer them to wire cooling racks to cool completely while you prepare the green cream cheese frosting.
In a large mixing bowl, combine the softened cream cheese, butter, vanilla extract, and a few drops of green gel food coloring.
Beat on medium speed until smooth and well blended.Gradually add the powdered sugar in increments, mixing thoroughly after each addition to achieve a fluffy, pipeable consistency.
If needed, add more green gel food coloring, a drop or two at a time, until you reach your desired vibrant shade of green. Transfer the frosting to a piping bag fitted with a star tip for easy assembly.
Pipe a small swirl of green frosting onto the center of the largest cookie, then gently press the medium-sized cookie on top, centering it carefully.
Add another swirl of frosting to the top of the medium cookie, and place the smallest cookie on that. (The star tip will create a beautiful, tree-like texture with each layer)
Finish each cookie tree by adding a generous dollop of green frosting to the top of the smallest cookie, then gently press a gold star sprinkle (or yellow candy star) into place to create the perfect tree topper.