Step 1

Preheat the oven to 375°F. Bring a large pot of water to a boil, add 2 tablespoons salt, then the pasta and cook to al dente (about 8 minutes). Drain and set aside.

Step 2

Meanwhile, melt the butter in a medium saucepan over medium-high heat. Add the onions and cook until soft and translucent, about 5 minutes.

Step 3

Add the flour, pepper and 1/2 teaspoon salt – whisk together well, making sure everything’s fully incorporated with the butter.

Step 4

Pour the milk into the saucepan all at once, bring to a boil, then reduce heat and simmer, whisking occasionally, until the mixture thickens – about 5 minutes.

Step 5

Remove the saucepan from the heat, add the cheese, and whisk until smooth.

Step 6

Add the pasta, chicken and peas to the sauce, and fold together to combine. Pour into a 2-quart baking dish, sprinkle with fried onions and bake for 20 minutes, or until it starts to bubble around the edges.