Cheesy ham and noodle bake combines diced ham, egg noodles, and a creamy cheese sauce in a comforting family casserole. This protein-rich dish is perfect for using leftover ham and pleases all ages.
Preheat the oven to 375°F. Lightly grease a 9x13-inch casserole dish with butter.
Bring a large pot of salted water to a boil. Add egg noodles and cook for 1 minute less than package instructions; drain well and set aside.
Melt the unsalted butter in a large saucepan over medium heat. Whisk in flour and cook, stirring constantly, for 1-2 minutes until the roux is lightly golden.
Gradually pour in the milk while whisking. Add onion powder, dry mustard, salt, and black pepper. Continue whisking over medium heat until thickened, about 3–4 minutes.
Reduce heat to low, then whisk in sour cream until smooth. Add shredded cheddar cheese (reserve 1/2 cup for topping) and stir gently until melted and smooth.
In a large mixing bowl, combine the cooked noodles, diced ham, frozen peas, and cheese sauce. Fold gently to combine without breaking the noodles.
Spread mixture evenly into the prepared casserole dish. Sprinkle the reserved 1/2 cup cheese over the top.
Bake uncovered for 20–25 minutes, or until bubbly and golden around the edges. If deeper browning is desired, broil for 1–2 minutes at the end, watching closely.
Let rest for 5 minutes before serving to allow the sauce to set for easy scooping.