Grand Orange-Cognac Liqueur

1/3 C orange zest (use a bitter type, like Seville or Haitian)
1/2 C granulated sugar
2 C cognac or French brandy
1/2 t glycerin
Place zest and sugar in a small bowl. Mash and mix together with back of wooden spoon or pestle. Continue mashing until sugar is absorbed into orange zest and is no longer distinct. Put into a container and add cognac. Stir, cap, and let age in a cool, dark place 2-3 months, shaking monthly.
After initial aging, pour through a fine-mesh strainer into a medium bowl. Rinse out aging container. Pour glycerin into aging container and place a filter or cloth bag in strainer. Pour liqueur back through filter into container. Cap, shake, and age 3 months.