This Instagram sensation started as a simple post. In 2016, Denver-based cake maker and Food Network Challenge winner Rachael Teufel was asked to create a cake inspired by an amethyst. She came up with a rock candy geode and shared a photo, and everyone went nuts. Now, with more than 48,000 posts, #geodecake is officially a thing: Beyoncé celebrated her birthday with a black-and-gold one. See how Rachael creates this gem.

All photographs by Rachael Teufel, Intricate Icings Cake Design.

Trim the cakes to make them level. Working on a turntable, stack the 6-inch cakes on a cardboard round, spreading the buttercream between them with an offset spatula. Stack the 8-inch cakes the same way on an 8-inch round.

Cover each layer cake with a thin layer of buttercream (this is the crumb coat), smoothing it with a bench scraper. Refrigerate until firm, 1 hour. Cover with more buttercream; chill overnight. (Reserve 1/2 cup buttercream for slide 5.)

Add the geode to the 6-inch layer cake: Using a paring knife, carve out an irregular piece from the side of the cake. Be careful not to cut deeper than one-third of the diameter of the cake in order to maintain the cake’s structure.