1Heat oven to 400°F. Spray 10-inch skillet with cooking spray; heat over medium-high heat. Cook onion in skillet 2 to 3 minutes, stirring occasionally, until crisp-tender.
2Stir in vegetable mixture, broccoli and Alfredo sauce; reduce heat to medium. Cover; cook 5 to 6 minutes, stirring occasionally, until hot. Spoon into ungreased 8-inch square (2-quart) glass baking dish.
3In medium bowl, stir Bisquick mix, milk and dill weed until soft dough forms. Drop dough by 9 spoonfuls onto hot vegetable mixture.
4Bake 18 to 22 minutes or until biscuits are golden brown.