Using an electric mixer, cream the butter and sugar until fluffy.
Mix in the black food coloring until well combined.
Finally, mix in the flour. The mixture will look crumbly and not wet.
You should be able to pick up some dough and form a ball with it in your hands. If the dough is too crumbly to form a ball, add a touch of water (up to 1/4 teaspoon) until the dough holds together.
Form the craquelin dough into a ball and place it between two pieces of parchment paper. Roll the craquelin dough out until it is 1/8 inch thick.
Freeze the rolled-out dough for 5 minutes, then use a 2.25" round biscuit cutter to cut six circles of craquelin. If you want to make more than 6 cream puffs, re-roll the leftover craquelin dough and cut two more circles of craquelin.
Refrigerate the craquelin until ready to use.