1/2 cup water
1-1/4 cups bran
50g (1-3/4ozs) butter
1 egg  
1/2 cup brown sugar
3/4 cup plain yogurt
1-1/4 cups flour  
1-1/4 tsp baking soda
1/4 tsp salt
1/2 cup chopped raisins  
  
Place water in a suitable microwave bowl. Heat 
until boiling (about 1 min).  Add bran and butter 
and stir until butter is melted and bran. Beat in 
sugar and egg. Blend in remaining ingredients. 
Spoon into double paper patty  cases or paper 
lined muffin cups. 

The batter for this recipe may be kept in a 
covered bowl in the refrigerator for about 
4 weeks. To cook, allow 30 seconds on high 
per muffin (dough at room temperature) or 45 
seconds per muffin  (refrigerated dough). 
Tested in a 600-700 watt oven, for 500 watt 
oven allow  15 seconds extra for every 
minute of cooking.  
  

Source: http://www.nancys-kitchen.com