Dye the macaron batter green with food coloring, mixing gently to distribute the color.
Pipe turtle shapes and round macarons onto a baking sheet lined with parchment paper or a silpat mat. The round macarons will act as the turtle shells. Tap the baking sheet on the counter a couple times to remove any air bubbles, then let sit at room temperature for 30 minutes. This will create the hard shell of the macarons.
Set your oven to 375F, heat for 5 minutes, then reduce the heat to 325F. Bake the macarons, one sheet at a time, for 6-8 minutes, rotating halfway through. After each batch, increase the heat to 375F, heat for 5 minutes, then reduce to 325F and pop the next sheet into the oven!
Allow the macarons to cool on the sheet for 2-3 minutes, then transfer to a wire rack to fully cool.
Draw markings and a smile onto the turtles and the shells. Pipe some ganache onto the top of the turtle macarons, then place the shell macarons on top.