Espresso Ice Cream

Mix sugar, butter, cornstarch, and espresso powder together in a saucepan until blended. Stir in milk. Bring to a boil over medium heat; cook and stir until thickened, about 2 minutes. Remove mixture from heat; stir in vanilla extract and let cool completely, 20 to 30 minutes. Stir in condensed milk and coffee-flavored liqueur.

Beat whipping cream using an electric mixer in a mixing bowl until stiff peaks form; fold into cooled milk mixture.

Pour mixture into an ice cream maker and freeze according to manufacturer's instructions, about 20 minutes. Transfer to an airtight container and freeze until firm, about 4 hours.