Azorean Milk Liqueur - cooking recipe

Ingredients

2 1/2 cups grappa or 2 1/2 cups unflavored vodka
2 cups whole milk
2 cups sugar
2 ounces bittersweet chocolate, grated (preferably 70%)
1/2 lemon, seeded and chopped, with rind

Preparation

Pour the grappa and milk into an impeccably clean half-gallon glass jar with a tight-fitting lid. Scoop in the sugar, chocolate, and lemon. Cover the jar tightly and shake well to help the sugar begin to dissolve. It will look curdled; that's as it should be, and it's perfectly safe. Set aside in a cool, dark place and shake or stir with a clean spoon every day for 10 days.
Set a cheesecloth-lined colander over a bowl and pour in the mixture. When the mixture has finished draining, squeeze the cloth to release as much of the liquid as possible, and discard the solids.
Line a sieve with a paper coffee filter. Pour in the liqueur and let the mixture drip through the clean bowl-this can take up to 24 hours. Change the filter when it becomes clogged with the residue from the liqueur.
Pour the liqueur into a decanter with a tight-fitting top. It will keep at room temperature for up to six months.