An edible astronomy-themed display. Cake, surrounded by candy, arranged on a reflective surface with a black background, creating the illusion of a galaxy suspended in space.

Step 1: Materials

You'll need...

Cake mix (or from-scratch cake batter)
Frosting for the cake (white / vanilla / buttercreme)
A microwave-safe bowl about 6" in diameter
About 1lb of white M&Ms
Sugar sparkles / decorative sugar
3 sheets of 30"x40" black foam board / presentation board
Enough reflective mylar sheet to cover a table top (roughly 4'x5' in my case)

Step 2: The Cake

Pour enough cake batter to fill the bowl about 3/4 full. Bake the cake in the bowl. I baked the cake in the microwave, since the bowl I had wasn't oven-safe. Chances are you'll get a rounded top. You'll need to cut this off with a large knife.

Step 3: Assembly

Cover the table top with the reflective mylar.
Place the cake, upside down, in the middle of the table.
Frost the cake in-place, filling in any gaps around the edge.
Arrange the M&Ms into spiral arms. I did four but you can do pretty much whatever looks good.
Flesh out the spiral arms with decorative sugar, adding some to the cake to help blend it with the arms.
Stand the display boards on the rear of the table.

The effect works best when viewed from a low angle, under diffuse lighting. Avoid spotlights and exposed fluorescent tubes.