Fudgy Oat Milk Gelato

Name: Fudgy Oat Milk Gelato
Ingredients: 2 3/4 cups + 3 tablespoons plain or vanilla unsweetened oat milk; 1/4 cup unsweetened cocoa (I use Hershey's Special Dark); 3/4 cup sugar; 1 tablespoon instant coffee powder or 1 1/2 teaspoons instant espresso powder; a pinch of salt; 3 tablespoons corn starch; 4 egg yolks, beaten; 2 tablespoons rum or coffee liqueur; 3 ounces dark chocolate, chopped and melted (I use the microwave on medium in 15-second increments, stirring frequently and stopping while there are still a few bits still visible)