Pour 2 cups of cold milk into a large mixing bowl. Add the instant vanilla pudding mix and whisk according to the package directions, usually about 2 minutes, until smooth. Let the pudding stand for the package’s recommended setting time until it is thick enough to mound softly on a spoon. If the mixture remains runny, check that you used a standard instant pudding mix and measured the milk correctly.
Add the 8-ounce tub of refrigerator-thawed whipped topping to the thickened pudding. Use a rubber spatula to gently fold the topping into the pudding, scraping the bottom of the bowl until no white streaks remain. Avoid vigorous whisking because that can deflate the filling and make it less fluffy.
Place 24 golden sandwich cookies, including their cream filling, into a food processor. Pulse until mostly fine crumbs form, leaving a few small pieces for texture. If you do not have a food processor, place the cookies in a sealed food-storage bag, press out the excess air, and crush them with a rolling pin.
Arrange eight clear, 8-ounce serving cups on a refrigerator-safe tray. Keep the prepared pudding filling, crushed cookie crumbs, and a small spoon or piping bag nearby for easy assembly.
Divide half of the prepared pudding filling evenly among the eight cups. Next, distribute the crushed cookie crumbs evenly among the cups so each one has a visible dirt layer. Spoon the remaining pudding filling over the crumbs, creating a pale top layer that resembles snow. Use two small spoons or a piping bag to keep the cup walls tidy. Leave some space below each rim for the Christmas Tree Cake decorations.
Cover the assembled dessert cups and refrigerate for at least 30 minutes to firm the filling. Longer chilling produces softer, more cake-like cookie layers. Adjust the chilling duration according to your preferred cookie texture.
Just before serving, unwrap eight Little Debbie Christmas Tree Cakes. Gently nestle the broad base of one cake into the pudding filling of each cup. If a cake leans, rest it against the inside rim for support. Finish each dessert with a light scattering of Christmas sprinkles, using approximately 2 teaspoons total or adjusting to taste. Serve chilled.