-And Half Combine the sugar and flour, in a large microwave-safe bowl, blending well, and then gradually stirin the milk. Blend in the egg and the backing chocolate pieces. Microwave on HIGH (100%) for 2 to 2.5 minutes, stirring frequently, or just until the mixture boils and thickens. Add the rum extract, blending it in, with a wire whisk, just until smooth and well blended. Chill thoroughly. Add the light cream to the chilled mixture and blend well. Freeze in a 2 litre ice cream freezer according to the manufacturer's directions.