Preheat oven to 350°F and grease cake pans.
Whisk flour, baking powder, cinnamon, and sugar in a large bowl.
In a second bowl, mix eggs, melted butter, milk, vanilla, and orange zest.
Combine wet and dry mixtures gently until smooth. Avoid over-mixing.
Divide batter into two pans and bake for about 30 minutes.
Let the cakes cool completely before frosting.
Prepare frosting by beating cream cheese and powdered sugar until light.
Separate frosting into three bowls, tinting each with galaxy colors.
Stack cakes and apply a crumb coat. Chill for 15 minutes.
Add galaxy frosting, swirling purple, blue, and black with an offset spatula.
Decorate with gold stars, edible glitter, and a Sagittarius constellation.
Add finishing touches using piping bags, shaping crisp astral lines.
