Step 1

Heat oven to 350°F. Spray 8-inch square (2-quart) glass baking dish with cooking spray.

Step 2

In 12-inch skillet, melt 1 tablespoon of the butter over medium heat. Add onion, bell pepper, corn and lima beans. Cook about 5 to 8 minutes, stirring frequently, until vegetables are crisp-tender. Remove vegetables to large bowl; set aside.

Step 3

In same skillet, melt remaining 2 tablespoons butter over medium heat. Stir in flour, thyme, salt, pepper and mustard with whisk. Cook 2 minutes, stirring constantly. Gradually stir in milk. Heat to boiling; cook and stir until sauce is smooth and bubbly. Remove from heat; stir in cheese until melted.

Step 4

Pour cheese sauce over vegetables; mix well. Pour mixture into baking dish. Sprinkle with bread crumbs.

Step 5

Bake uncovered 20 to 30 minutes or until bubbly and topping is golden brown.