3 tbsp. butter, divided
1 (8 ounce) package uncooked medium egg noodles
1/2 medium onion, finely chopped
1 clove garlic, minced
8 ounces button mushrooms
2 tbsp. corn starch
2 cups broth
salt and pepper to taste
3 (6 ounce) cans tuna, drained and flaked
1 cup frozen peas, thawed
1 package onion soup mix
Preheat oven to 375°F. Spray a medium baking dish with cooking spray.
Bring a large pot of lightly salted water to a boil. Add egg noodles, cook for 8 to 10 minutes, drain.
Melt 1 tablespoon butter in a skillet over medium-low heat. Stir in the onion and garlic, and cook 5 minutes, until tender. Increase heat to medium-high, and mix in mushrooms. Continue to cook and stir 5 minutes, or until most of the liquid has evaporated. Add the rest of the butter and whisk in corn starch until smooth. Gradually whisk in broth and onion soup mix, continue cooking 5 minutes, until sauce is smooth and slightly thickened. Season with salt and pepper. Stir in tuna, peas, and cooked noodles. Transfer to the baking dish.
Bake 25 minutes in the preheated oven, or until bubbly and lightly browned.