To color the macarons, add a few drops of natural brown food coloring in Step 4 of the master recipe.
For the filling: Pipe a ring of chestnut cream around the border of half of the macarons using a piping bag and a #2 tip.
Combine the remaining ingredients in a bowl using a whisk. Stir until the sugar has dissolved. Transfer to a piping bag.
Have half of the macarons flipped over (flat side up) and ready to be filled. Pipe the filling onto the macaron bases. Place the top macaron over the filling and gently push down. Reserve refrigerated.