Preheat oven to 350° Spray a 2-quart baking dish with nonstick spray; set aside. Cook pasta in boiling water 9 to 11 minutes or until pasta is al dente; drain.

Melt 4 tablespoons butter in a large saucepan over medium heat until melted. Whisk in flour, salt, and garlic powder until well combined. Slowly whisk in milk. Cook and whisk over medium-low heat 5 minutes or until thickened.

Stir in 2 cups Havarti and queso blanco. Cook and stir 2 minutes or until cheeses are melted; remove from heat. Add cooked pasta, chicken, corn, and tomatoes with green chilies; stir to combine. Spoon pasta mixture into the prepared baking dish. Top with remaining 1 cup Havarti.

Microwave remaining 2 tablespoons butter in a medium microwave-safe bowl 30 seconds or until melted. Stir in bread crumbs until evenly coated. Sprinkle bread crumb mixture on top of casserole. Top with jalapeño slices and cherry tomatoes. Bake 20 to 23 minutes or until edges begin to bubble; remove from oven.

Place oven rack 6 inches from heat. Preheat broiler to HIGH. Broil casserole 2 to 3 minutes or until crumbs are golden brown. Let stand 10 minutes before serving.