Easy Tuna Casserole

Since I haven't been to the grocery store in a week, I wasn't sure what to make for dinner. Matt suggested the tuna casserole I've made a few times now. It's so easy, I feel bad serving it!

Easy Tuna Casserole
Measurements are estimated
1 package macaroni and cheese
1/4 cup milk
4 tablespoons butter
1/2 cup diced onions
1 teaspoon butter
1 can tuna packed in water, drained
3/4 cup shredded cheddar cheese, divided
1/4 teaspoon chili powder
1/4 teaspoon cayenne pepper
1 cup frozen peas
1/2 cup panko bread crumbs
1 tablespoon butter

Preheat oven to 350 degrees F. Melt 1 teaspoon butter in small skillet. Add onions and sweat until translucent but not browned. Meanwhile, prepare the macaroni and cheese following the package directions. Once butter, milk and cheese mix are incorporated, stir in onions, tuna, 1/2 cup cheddar cheese, chili powder, and cayenne pepper. Once cheese is melted, stir in the peas. Pour mixture into a greased 2-quart casserole dish. Top with remaining 1/4 cup cheddar cheese. Melt 1 tablespoon butter. Add to panko and stir well to coat. Sprinkle panko evenly over casserole. Cover with aluminum foil and bake for 35 minutes. Remove foil and bake for another 10 mintues until the topping is browned. Remove from oven and let stand for 15 minutes to set up.