Baked Penne with Chicken and Sun-Dried Tomatoes (Freezer Meal)

6 T. butter
salt and pepper
1 lb. penne rigate
1 t. olive oil
l lb. boneless skinless chicken
1/2 C. plus 2 T. all-purpose flour (spooned and leveled)
4 garlic cloves, minced
6 C. whole milk
10 oz. white mushrooms, sliced
1/2 C. sun-dried tomatoes (either drained of oil, or I found some in a bag)
1 1/2 C. shredded provolone (I used mozzarella)
1 C. finely grated parmesan

Butter two shallow 2-quart baking dishes.  In a large pot of boiling salted water, cook pasta 3 minutes short of normal; drain pasta and return to pot.  In a large nonstick skillet, heat oil over medium-high.  Season chicken with salt and pepper.  Cook through.  Slice thinly crosswise.  In a 5 quart heavy pot, melt butter over medium.  Add flour and garlic; cook, whisking, 1 minute.  While whisking, gradually add milk;  bring to a simmer, whisking frequently.  Add mushrooms and tomatoes; cook 1 minute.  Off heat, gradually stir in provolone and 1/2 C. Parmesan.
Add chicken and pasta to pot, season with salt and pepper.  Divide pasta mixture between baking dishes, sprinkle with remaining cheese.  Cook immediately or wrap with tinfoil and freeze.

To serve, thaw in refrigerator and bake uncovered at 400 degrees until top is golden and bubbling, about 25 min.  Let stand 5 minutes before serving.