In a medium skillet, heat butter over medium heat just until melted. Add peaches and brown sugar. Cook about 3 minutes or until mixture begins to bubble, stirring occasionally.
Stir in blueberries and lemon peel and continue cooking about 3 minutes or until fruit is just heated through. Stir in brandy or liqueur, if you like. Makes 2-1/2 cups sauce (8 servings).
Serve warm over ice cream, spoon over pancakes for brunch, or ladle over crepes, pound cake, gingerbread, or scones.