In small microwave-safe bowl, combine baking bar and 1 tablespoon of the half-and-half. Microwave on HIGH for 30 seconds; stir until melted and smooth. If necessary, microwave an additional 10 to 20 seconds. With wire whisk, beat in powdered sugar until smooth. If necessary, add additional half-and-half, 1/2 teaspoon at a time, until of desired consistency. Spoon and spread icing over cooled loaf, allowing some to run down sides.