Vegetable Au Gratin Casserole

2 Tbsps butter
1/2 tsp salt
1/2 tsp pepper
2 Tbsps flour
2 cups milk
3 cups shredded cheddar cheese
1 1/2 cups asparagus tips (3 inch piece)
1 1/2 cups baby carrots
1 1/2 cups broccoli florets
1 cup cauliflower
1 celery stalk – chopped
1 cup diced yellow onion
1 1/2 cups mushrooms – sliced
1 1/2 cups yellow, straight neck squash – sliced
2 med red potatoes – quartered

• Preheat oven to 400 degrees.
• Melt butter in a sauté pan over medium heat and add salt and pepper.
• Reduce heat to medium-low and add flour to create a roux; using a wire whisk, stir the butter-flour mixture constantly until it bubbles for 1-2 minutes.
• Slowly add milk to the roux, stirring vigorously with the wire whisk.
• Cook and stir constantly over medium heat until the sauce thickens.
• When the sauce is thickened and just begins to boil add cheddar cheese, continue stirring and cook until cheese is completely dissolved.
• Remove from heat.
• Add vegetables to cheese sauce, mix and transfer to a 2 quart casserole dish.
• Cover and bake at 400 degrees for 1 hour and 45 minutes.