in a small bowl, combine 2 tablespoons cornstarch, 1/4 teaspoon salt, and 1/4 cup sugar. use 1/2 a cup of strongly brewed coffee, and in a saucepan, combine the coffee with 1 and 1/2 cups of heavy cream. bring to a simmer over medium heat, and start adding the cornstarch-sugar-salt mixture, using a whisk to combine.