Tuna Artichoke Casserole

1/2 medium onion, chopped
1/2 cup mushrooms, sliced
1/2 cup chicken broth
2 tablespoons flour
1 1/2 cups milk
1 can tuna, drained 
1 can artichoke hearts, diced
1/2 cup Mexican cheese blend
2 1/2 cup uncooked pasta shells
salt & pepper, to taste

1.Preheat oven to 350 degrees.

2. Cook pasta according to package directions.

3. In medium saucepan, saute onions until tender. Add in mushrooms and saute until almost tender. In small bowl, combine chicken broth and flour. Reduce heat to medium and add chicken broth mixture to onions. Slowly whisk in milk. Cook until sauce thickens. Reduce heat to low.

4.. Add in tuna, artichoke hearts and cheese. Season with salt and pepper.

5. Transfer into baking dish. Bake for 25 minutes or until hot and bubbly.