Place an oven rack in the center of the oven, then preheat to 350°F. Melt the butter in a large bowl in the microwave (or melt in a small pot on the stove; transfer to a large bowl). Add the brown sugar, cream (shaking the packet before opening), egg, and all but 1 tablespoon of the granulated sugar; whisk to combine. In a separate bowl, combine the flour, baking powder, and half the warming spices. Transfer the dry ingredients to the bowl of wet ingredients. Stir until no white streaks remain.

Lightly grease a loaf pan. Transfer half the batter to the pan and spread into an even, roughly 1/4-inch layer. Evenly top with the cream cheese frosting. Scoop the remaining batter on top of the frosting, then spread in an even layer, ensuring almost all of the frosting is covered.

In a bowl, combine the remaining warming spices and remaining granulated sugar. Evenly top the batter with the spiced sugar mixture. Bake 28 to 32 minutes, or until set and cooked through. Remove from the oven and let cool completely. Once cooled, remove from the pan and slice into equal-sized bars. Enjoy!