Bring 2 quarts of water and 1 teaspoon salt to a boil in a large saucepan. Add the ground beef and stir vigorously to separate the meat. After about 30-45 seconds, before the water returns to a full boil, drain the meat into a strainer and set aside.
Add the ground beef back to the pot and turn the heat to high. Once the chili is boiling, reduce the heat to medium-low and simmer uncovered, stirring occasionally, until the chili has thickened slightly, approximately 1 hour. Stir in the bittersweet chocolate and simmer an additional 5 minutes. Taste; add cocoa powder if the chili tastes too sweet (the bitterness of the cocoa powder will balance). Season with additional salt as desired.
Try to use bittersweet chocolate that’s at least 70% cacao. Some bittersweet chocolate is as low as 60% cacao, which is closer to semi-sweet chocolate and could result in a sweeter chili. Adding the cocoa powder at the end will offset any sweetness and add richness. Start with 1 teaspoon, taste, and then add the second teaspoon if needed. Alternately, you can omit the bittersweet chocolate entirely, and instead add 2 teaspoons cocoa powder + 2 teaspoons dark brown sugar.
Adapted from More Best Recipes by America’s Test Kitchen