For a change from Coffeemamma's recipe. These are more like small cakes than muffins, and you don't get quite the same honest tang of rhubarb when it's sweetened up with the brown sugar--but they are still very good.
Upside-down Rhubarb Muffins
(from The Harrowsmith Cookbook Volume 3, sent in by Joan Alrey of Rivers, Manitoba)
1 cup "finely" chopped rhubarb (we just diced ours with a knife)
1/4 cup melted butter or margarine
1/2 cup packed brown sugar
Another 1/3 cup soft butter or margarine
1/3 cup sugar
1 1/2 cups flour
2 tsp. baking powder
1/2 tsp. salt
1/2 tsp. nutmeg
1/2 cup milk
Ponytails made the topping: she melted the 1/4 cup margarine in the microwave and then mixed in the rhubarb and brown sugar and dropped the mixture into the 12 holes of a muffin pan (greased first). Mama Squirrel made the batter: she blended the margarine, sugar and egg and then mixed in the dry ingredients alternately with the milk, stirring just to moisten. We spooned the batter (it was fairly stiff) on top of the rhubarb, and baked it at 350 degrees F for 20 to 25 minutes.
Now this is the little trick at the end: get your cooling rack ready (with some waxed paper underneath if you're nervous). When the muffins are done, take them out and dextrously invert the whole thing on the cooling rack--but leave the pan on top of the muffins for a few minutes to let all the rhubarb moisture run out. (It's not really that messy.) Serve them warm if you can (otherwise you might have to refrigerate them).