Step 1

Season chicken with 3/4 teaspoon salt and 1/2 teaspoon pepper.

Step 2

Melt butter in a Dutch oven over medium heat. Working in batches, add chicken to the skillet in a single layer and cook until golden brown, about 7-8 minutes; set aside.

Step 3

Add mushrooms and shallots, and cook, stirring occasionally, until tender, about 3-4 minutes.

Step 4

Stir in garlic and thyme until fragrant, about 1 minute.

Step 5

Whisk in flour until lightly browned, about 1 minute.

Step 6

Stir in chicken stock and Dijon, scraping any browned bits from the bottom of the Dutch oven.

Step 7

Stir in fusilli; season with salt and pepper, to taste.

Step 8

Bring to a boil; reduce heat and simmer, stirring occasionally, until pasta is just al dente, about 8-9 minutes.

Step 9

Stir in chicken, spinach, Parmesan and heavy cream until spinach has wilted and pasta is tender, about 3 minutes.

Step 10

Serve immediately.