Serves about 25.
Prepare Chocolate Ganache following recipe instructions. Cool slightly.
Cover cake circle with foil; spread 2 tablespoons ganache onto covered circle. Arrange 3 cream puffs in triangle shape in center of cake circle; form a ring of about 9 cream puffs around triangle. Create next layer by dipping one edge of cream puffs, one at a time, into ganache; arrange in a slightly smaller ring on top of first cream puff ring. Place additional cream puffs to fill center of ring. Continue building remainder of tree in same fashion, creating smaller rings on each level. Finish with a single cream puff at the top.
If necessary, gently heat remaining ganache to thin. Using spoon, drizzle over cream puff tree. Refrigerate to set; keep refrigerated until ready to serve.