Step 1

Preheat oven to 350°F.

Step 2

In a large pot of salted boiling water, cook egg noodles according to package directions. Drain and set aside.

Step 3

In a large saucepan over medium heat, melt the butter. Whisk in flour and continue whisking 1 to 2 minutes, until raw flour taste is cooked out.

Step 4

Gradually whisk in milk, chicken stock, and heavy cream. Whisking frequently, cook until mixture comes to a bubble and thickens, about 10 minutes. Stir in garlic powder, onion powder, and thyme. Season with salt and pepper.

Step 5

Remove from heat and stir in sour cream, chicken, noodles, mushrooms, and 1/2 cup of the mozzarella. (You can stir together in the casserole dish if your pan isn't big enough.)

Step 6

Transfer mixture to a casserole dish and top with remaining mozzarella cheese. Mix together melted butter and breadcrumbs and sprinkle over the top. Bake until bubbly and lightly golden, about 30 minutes.

Step 7

Let rest 5 minutes before serving. Enjoy!