1. Place the flour and margarine in a microwave-safe bowl (2 1/2 liter or 2 1/2 quart). Cover with a vented microwave lid and cook on HIGH (1200W) for 40 - 60 seconds to melt margarine.

2. Take out and stir with a wire whisk until it becomes pasty. Add 1/2 cup milk and stir more until it becomes creamy. Add remaining milk. Cover and cook on HIGH (1200W) for 2 minutes. Take out, add salt and pepper, cover and cook on HIGH (1200W) for 2 more minutes. Stir until it becomes smooth and creamy <White Sauce>.

3. Blend cheddar cheese into the <White Sauce> and stir until the cheese melts. If cheese does not melt, cook on HIGH (1200W) for 1 – 2 minutes and stir.

* This will make a great pasta sauce! For a fish or chicken casserole sauce! This can be spread on bread and toasted! This cheese mixture can be used for <Welsh Rarebit>.

For how long you should cook with your microwave oven, see Cooking Time vs Wattage Conversion.
For more tips of using Microwave Oven, see Sachiko's Guideline to Microwave Cooking.