This was pretty good. I was really hoping it would be better though....I love myself some casseroles! It wasn't uber flavorful - but B liked it :)
8 ounces medium shell pasta, cooked al dente according to package directions
4 tablespoons butter, divided
1 medium stalk celery, thinly sliced or diced
¼ cup diced onion
8 ounces mushrooms, sliced or diced
olive oil, as needed
4 tablespoons flour
14.5 ounce can chicken broth (just under 2 cups), warmed
1 cup milk, warmed
¼ teaspoon kosher salt
1/4 teaspoon black pepper
⅛ teaspoon dill
2 teaspoon fresh lemon juice, more if desired (I desire)
2 tablespoons fresh minced parsley
1 cup freshly grated Parmesan cheese, divided
5 oz can tuna, packed in water, more if desired
1/4 cup Ritz cracker crumbs or 1/4-1/2 cup broken up potato chips (I recommend kettle style)
Melt 1 tablespoon butter in a large skillet. Add celery and sauté for 2-3 minutes. Add onion and cook 2-3 minutes longer, stirring often. Add mushrooms and cook 3-5 more minutes, until mushrooms are golden and tender. If needed for moisture, add a drizzle of olive oil to the pan after the mushrooms are added; more if needed during remaining cooking time. Remove vegetables from pan and set aside.
Melt remaining 3 tablespoons butter in pan and add flour. Stir constantly for 30 seconds. Slowly add broth and milk, a little at a time while constantly whisking until mixture is smooth. Bring to a low simmer. Add salt, pepper, and dill. Stir constantly until thickened and bubbly, 2-3 minutes. Reduce heat to low and add lemon juice, parsley, and 1/2 cup Parmesan cheese. Whisk until smooth and taste. Season with additional salt and pepper to taste, and extra lemon juice if desired. Remove from heat and add pasta, vegetables, and tuna. Stir to combine and place in a 3 quart baking dish. Sprinkle with remaining 1/2 cup cheese (feel free to add more if you want) and sprinkle cracker crumbs or chips on top.
Bake at 350 for 25-30 minutes, until top is golden and pasta is hot and bubbly. Let rest 10-15 minutes before serving to allow sauce to thicken.