Preheat the oven to 350F. Butter and flour an 8-inch cake pan, and set aside.

In the bowl of a stand mixer, beat the butter, granulated sugar, and orange zest until light and fluffy.

Add in the eggs, one at a time, beating well between additions.

Add in the flour and baking powder, mixing until just combined.

Add in the sangria, and mix until incorporated. If desired, add in a couple of drops of red and purple food coloring to reach your ideal color.

Pour the batter in the prepared pan, and bake for 20 minutes, then cover the pan with foil, and bake for 10 minutes longer.

When cake is ready, remove from oven and let cool completely before frosting.

When ready to frost, beat together the butter, zest, salt, and powdered sugar until creamy.

Mixture should be very thick, so add in the heavy cream, a little at a time, until you reach your desired consistency. Spread the frosting on the cake, and top with the orange slices.

Serve immediately, and store leftovers in the fridge. Enjoy!