In a 10-in. skillet, combine the first five ingredients. Add peaches; bring to a boil. Place egg in a 1-cup measuring cup; add enough milk to equal 1/2 cup. Place biscuit mix in a bowl; stir in milk mixture with a fork just until moistened. Drop by six spoonfuls over top of boiling fruit. Simmer, uncovered, for 10 minutes; cover and simmer 10 minutes longer or until dumplings test done. Sprinkle with cinnamon if desired. Serve warm with whipped cream of desired. Yield: 6 servings.