Preheat oven to 400°F.

Bring a pot of water to a boil.

Add pasta shells and cook until al dente.

Remove pasta from water and arrange on a sheet of wax paper to cool. Make sure they are not touching so they won't stick together.

Mix the soup, milk, peas, and tuna in a bowl.

Put a thin layer of tuna mixture on the bottom of a casserole dish.

Fill shells with mixture and place in the casserole dish.

Bake the tuna mixture for 20 minutes or until hot and bubbling.

Melt butter and add bread crumbs and sprinkle them over the shells.

Bake for 5 minutes more, or until the bread crumb mixture is golden brown.