Tuna Tetrazzini | Lazy Cooking

Ingredients

• 13.5 ounces thin spaghetti
• 4 tablespoons butter, divided
• 1/2 cup onion, diced
• 1/2 cup celery, diced
• 1/4 cup flour
• 2 cups milk
• 2 cups cheddar cheese, shredded
• 1 teaspoon salt
• 1/2 teaspoon Cajun seasoning
• 1/2 cup frozen peas, thawed
• 1 1/2 cups fresh tuna, cooked, can substitute canned tuna, drained and shredded
• panko breadcrumbs, to taste