LEMON WALNUT MUFFINS

1 cup sugar                                          2 Tbsps. grated lemon peel
1/2 butter                                             1 tsp. baking soda
2 eggs                                                   1 1/2 cups coarsely chopped walnuts
1 cup plain yogurt                               2 cups flour

Cream sugar and butter until pale and fluffy.  Beat in eggs then add yogurt, lemon peel, baking soda and walnuts.  Add flour gradually, mixing until well blended.  Spoon into greased or paper lined muffin cups.  Bake at 350º for 18 - 20 mins.