Fill a large pot with water and bring it to a boil over medium-high heat. Once boiling, stir in the pasta. Wait for the water to return to a boil, and cook the pasta for six minutes. After six minutes, add the beans and broccoli and boil for an additional two minutes.After two minutes, remove the pot from the heat.
 Pour the pasta and vegetables into a large colander to drain the water. Rinse everything with cold water to remove excess starch. Let the pasta and vegetables drip dry for a couple minutes, then return them to the pot.Set the pot aside while you cook the remaining ingredients.
 Pour the oil into a large skillet and heat it over medium heat. When the oil is shimmering, add the mushrooms, pepper, and chicken. Season with the Italian seasoning, and salt and pepper, to taste. Cook the mixture for six to eight minutes, until there’s no pink left in the chicken.Once cooked, transfer the chicken mixture to the pot with the pasta, beans, and broccoli.
 Transfer the butter to a medium saucepan and melt it over medium heat. Add the garlic and onion. Cook for five to seven minutes, until the onions become soft and aromatic. Whisk in the flour, tomato paste, and milk.

Continue cooking until the mixture simmers and becomes thick, about five to six minutes., Turn the heat to low. Add the cheese and keep stirring until the cheese is melted. Remove the saucepan from the heat, and whisk the cheese sauce until the cheese and base are fully combined.

Season with salt and pepper, to taste.
You can use any processed cheese in place of the Velveeta, such as slices of processed American or Swiss cheese.
To make a spicy cheese sauce, add a pinch of cayenne pepper and a sprinkle of red pepper flakes., Pour the cheese sauce into the pot with the pasta, chicken, and vegetables. Stir to combine. Transfer the casserole mixture to a baking dish or casserole dish that’s freezer- and oven-safe. Place it into the refrigerator uncovered, and let it cool for an hour.

You’ll need a baking or casserole dish that can hold 3 quarts (2.8 L) for this casserole recipe., Once cooled, cover the casserole with an airtight lid or tightly with plastic wrap. For short-term storage, keep the casserole in the refrigerator and eat it within four days. For longer-term storage, keep the casserole in the freezer and eat it within four months., When you're ready to eat the casserole, remove it from the freezer and let it thaw in the refrigerator overnight. When the casserole is thawed, cover it with foil and bake it in a preheated 350 F (177 C) oven for 75 minutes. In the final half hour, uncover the casserole and sprinkle the panko on top. Finish baking the casserole uncovered.

As the casserole bakes, stir it every 30 minutes to ensure it heats evenly throughout.
Cook the pasta, beans, and broccoli.
Drain and rinse.
Cook the chicken and remaining vegetables.
Make the cheese sauce base.
Add the cheese.
Combine all ingredients and transfer to a casserole dish.
Freeze or refrigerate.
Bake when ready.
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