Brown Sugar Muffins

1/2 c. butter, 1 egg, 1/4 tsp. salt, 1 tsp. vanilla, 1 c. nuts (optional), 1 c. brown sugar, 2 c. flour, 1 tsp. soda, 1 c. milk. Bake 375 for 15 minutes. Sprinkle with brown sugar and sugar before serving. Makes approx. 2 dozen muffins.