Chop chocolate into small dice. Put mixer bowl and whisk into the freezer.
In a small saucepan over medium heat, bring cream to a slow boil. Remove from heat and stir in chocolate, butter, and liquor, if using. Wait 2-3 minutes for chocolate to soften. Whisk to smooth and combine everything.
Remove mixer bowl and whisk attachment from freezer. Transfer mixture to mixer bowl and whisk at medium until thick and smooth. Add a tbls of cream if it's looking curdled or oily. Be sure to scrape down the size so everything is captured. It should look like chocolate frosting; smooth and glossy. Cover and refrigerate at least 4 hours.
Pour powder cocoa into a pie plate. Remove ganache from refrigerator and make 24 (approximately) balls. Scoop out a small amount of ganache with a melon baller or tablespoon. Roll into a ball and set aside on a plate. When done, put rolled balls in refrigerator for 15 minutes to chill a bit.
Roll each ball in cocoa powder, shaking off excess. Place balls in one layer into whatever container you'll be using to hold them. Eat a room temperature.