For the cake: Preheat the oven to 350 degrees F. Grease and flour a nonstick 9-by-13-inch pan.
Whisk the flour, baking powder, baking soda and salt in a large bowl and set aside. Melt the butter in a saucepan over medium heat until bubbling. Stir in the cinnamon, allspice, black pepper and 1 tablespoon ginger and cook until fragrant, about 30 seconds. Let cool slightly.
Whisk the sugar, eggs and remaining 1 tablespoon ginger in a large bowl until light and frothy. Stir in the melted butter mixture, beer and molasses until incorporated. Whisk the flour mixture into the egg mixture until no lumps remain. Pour the batter into the prepared pan and gently tap the pan on the countertop to release any trapped air bubbles. Bake until a toothpick inserted in the center of the cake comes out clean, about 15 minutes. Let cool completely.
For the spiced cream cheese buttercream: Put the white chocolate chips in a heatsafe bowl and set aside. Bring the sugar and 3 cups water to a boil in a saucepan and reduce the heat. Mix the cornstarch with 1 cup water and add it to the hot liquid. Bring it back to a boil, then pour it over the white chocolate chips. Let cool to room temperature.
Add the butter and vanilla to the white chocolate chip mixture and mix with a whisk until light and fluffy. Fold in the cream cheese, cinnamon and ginger.
Slice the cake into 1-inch cubes. Mount the cubes on lollipop sticks and frost generously with the buttercream. Enjoy.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.