Cottage Pudding with Lemon Sauce

1 Egg 1 Cup Milk 3/4 Cup Sugar 2 Cups Flour 3 Tbsp Melted Butter 4 Tsp Baking Powder 1/4 Tsp Salt   Beat egg, add sugar, butter and milk. Add flour, salt and baking powder. Beat. Bake in shallow, greased pan for 25 to 30 minutes at 350 deg. Serve with the following lemon sauce:   2 Cups Boiling Water 1 Tbsp Cornstarch 1 Cup Sugar 1 Tbsp Butter Grated Rind And Juice Of One Lemon   Mix sugar and cornstarch, pour into the boiling water. Simmer five (5) min., stirring occasionally. Remove from heat; add lemon rind, juice and butter. Stir till butter is melted and serve.