Heat 1/4 cup (1/8 lb.) butter or margarine in a heavy pan over medium heat; add 1 large onion, (chopped) and saute until limp.
Stir in 1 clove garlic (mashed) and 2 tablespoons curry powder; cook about 1 minute more.
Add 4 tablespoons all-purpose flour, 1 tablespoon cornstarch, 2 tea spoons sugar, 1/2 teaspoon salt, and dash cayenne; stir over medium heat until blended and bubbly.
Gradually stir in 2 cups regular strength chicken broth and 1 cup whipping cream; cook until thickened.