Tuna Fusilli

This recipe is from my Saving Dinner cookbook. I used Wacky Mac pasta instead of fusilli.

12 oz. fusilli
2 T. butter, divided
1 onion, chopped (I used less onion)
1 clove garlic, pressed (I used garlic powder this time)
1 12-oz. can tuna in water, drained ( I used 2-5 oz. cans)
1 tsp. basil (I did not use)
1 jar roasted peppers, diced (I have used this before, but not this time)
1 package frozen green beans, thawed (I used frozen peas this time)
2 tsp. flour
1 cup milk
1/2 cup low-fat Cheddar cheese, shredded (I used regular, not low-fat)
Salt and pepper to taste

Cook pasta according to package directions, drain, and set aside.
In a skillet over medium heat, melt 1 tablespoon butter. Add onion and garlic and saute till translucent. Add drained tuna and basil, mixing well. Add diced peppers and green beans; mix well and remove from skillet.
In the same skillet over medium heat, add remaining butter and add flour gradually, whisking well to form a roux. Add milk and keep whisking till mixture is fully incorporated. Keep whisking and add cheese. Allow sauce to thicken, careful to not let it boil.
Add tuna mixture and pasta back to the cheese sauce, add salt and pepper to taste, and serve.