In a medium bowl, whisk the prepared vanilla pudding with the chilled eggnog until smooth and creamy. The mixture should be pourable but thick enough to coat the back of a spoon. If it seems too thin, chill for 15–20 minutes so it sets slightly.
3 cups prepared vanilla pudding, 2 cups eggnog
In a large, cold mixing bowl, combine the heavy whipping cream, granulated sugar, powdered sugar (if using), vanilla extract, and rum extract. Beat with a hand mixer or stand mixer on medium-high speed until soft peaks form, about 3–4 minutes. The cream should be thick and fluffy but not stiff or grainy.
2 cups heavy whipping cream, 1/3 cup granulated sugar, 1/4 cup powdered sugar, 1 teaspoon pure vanilla extract, 1/4 teaspoon rum extract
Gently fold the ground nutmeg, ground cinnamon, and a pinch of fine sea salt into the whipped cream until evenly distributed. Taste and adjust the spices or rum extract if desired, being careful not to overmix.
1/2 teaspoon ground nutmeg, 1/2 teaspoon ground cinnamon, 1 pinch fine sea salt
Cut the sponge cake or pound cake into 1-inch cubes. If the cake is very fresh and soft, let the cubes sit out for 10–15 minutes so they dry slightly and hold up better in the trifle.
1 pound sponge cake or pound cake
Place an even layer of cake cubes in the bottom of a large trifle bowl or clear glass bowl (about 3–4 quarts). If you want a stronger eggnog flavor, lightly brush the cake with a small amount of eggnog or eggnog mixed with a splash of rum or bourbon (optional).
1 pound sponge cake or pound cake, 2 cups eggnog
Spoon about one-third of the eggnog-pudding mixture over the cake layer, gently spreading it to the edges so the layer is visible from the outside of the bowl. Avoid pressing down; you want soft, distinct layers.
3 cups prepared vanilla pudding, 2 cups eggnog
Spoon about one-third of the whipped cream over the pudding layer. Spread gently with an offset spatula or the back of a spoon. If desired, sprinkle a small pinch of nutmeg or a few cookie crumbs between layers for extra flavor and texture.
2 cups heavy whipping cream, 1/2 teaspoon ground nutmeg, 1/2 cup crushed gingersnaps or shortbread cookies
Repeat the layering process—cake cubes, eggnog pudding, whipped cream—until you have 2–3 full sets of layers, depending on the size of your bowl. Aim to finish with a generous layer of whipped cream on top.
1 pound sponge cake or pound cake, 3 cups prepared vanilla pudding, 2 cups eggnog, 2 cups heavy whipping cream
On the final whipped cream layer, dust lightly with additional nutmeg and cinnamon. Sprinkle crushed gingersnaps or shortbread cookies over the top, and add sugared cranberries or festive sprinkles if desired.
1/2 teaspoon ground nutmeg, 1/2 teaspoon ground cinnamon, 1/2 cup crushed gingersnaps or shortbread cookies, sugared cranberries or festive sprinkles
Cover the trifle bowl tightly with plastic wrap and refrigerate for at least 4 hours and up to 24 hours. Chilling allows the cake to absorb some of the eggnog and pudding so the trifle becomes creamy and spoonable, with the flavors melding together.