1. To make the <Chocolate Cake>, grease a 10x6x2 glass pan with margarine; lightly flour and chill.

2. Shift together the flour, baking powder, cocoa, and salt.

3. Beat the margarine or butter, brown sugar, and vanilla extract in bowl on high speed for 2 minutes or until creamy.

4. Beat in 1 egg.

5. Fold in 1/4 of the flour mixture.

6. Alternately, add remaining eggs and flour. Mix until smooth.

7. Pour the mixture into the pan. Cover with plastic wrap and poke a hole in the center to release the steam.

8. Place a bacon rack on the turn table, and center the pan on the bacon rack.

9. Cook on LOW(30%) for 16 – 18 minutes. When an inserted toothpick emerges perfectly clean, the cake is done. Remove from the pan and cool on a rack.

10. To make the <White Chocolate Sauce>, place white chocolate in microwave-safe bowl. Cover with a vented microwave lid and cook on HIGH(1200W) for 1 minute.*

11. Stir the chocolate until it is smooth. Stir in heavy cream and milk.

12. For <Decorating>, put 2 tablespoons sauce on each serving plate. Place a piece of cake in the sauce and sprinkle with shaved white chocolate and confectioner sugar; garnish with a sprig of mint.

* No need to break the chocolate; microwaves cooks the food from within.

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.