How to Make It
Beat spinach, cream cheese, paprika, salt, pepper, onion powder, and 2 of the grated garlic cloves with a stand mixer fitted with a paddle attachment on medium speed until combined, 1 to 2 minutes. Add scallions, mozzarella, Parmesan, and 3/4 cup of the pepperoni; beat until combined, about 1 minute. Set aside.
Roll pizza dough out on a lightly floured work surface to a 13- x 11-inch rectangle, with the 11-inch side facing you. Cut a large triangle out of the dough, making 1 cut from each bottom corner of the rectangle to the top middle point of the rectangle. (You will end up with 1 large triangle, plus 2 smaller triangles from the remaining dough.)
Preheat oven to 400°F. Line a baking sheet with parchment paper. Place large dough triangle on baking sheet; spread evenly with spinach-cheese mixture. Place 2 smaller dough triangles side-by-side on spinach-cheese mixture, covering large triangle completely and matching shape. Make 10 to 12 horizontal cuts on each half of the tree, but do not cut all the way across; leave a 1/2-inch strip down the middle of the tree. Using your fingers, gently twist dough strips created on each half of the tree to make tree branches.
Bake in preheated oven until golden brown, about 20 minutes. During final few minutes of bake time, microwave butter and remaining grated garlic clove in a small microwavable bowl on HIGH until butter melts, 30 seconds to 1 minute.
Brush butter mixture over warm baked tree. Decorate with remaining 2 tablespoons pepperoni in a garland pattern.