Instructions:
- Cook the pasta according to package directions for al dente (about 2 minutes less than recommended). During the last 3 minutes of cooking, add the broccoli florets to blanch. Drain well, reserving about 1 cup of the starchy pasta water.
- While the pasta cooks, season the diced chicken well. Heat olive oil in a large, deep skillet over medium-high heat. Sauté chicken until golden brown and cooked through (165°F/74°C). Remove chicken and set aside, leaving drippings in the pan.
- Reduce heat to medium. Add the butter to the pan drippings and let it melt. Whisk in the flour vigorously to form a smooth paste (roux). Cook for 1 minute, whisking constantly.
- Whisk in the minced garlic. Gradually pour in the chicken broth while whisking constantly to ensure no lumps form. Bring to a gentle simmer, then stir in the heavy cream.
- Allow the sauce to simmer gently for 3-5 minutes until it thickens enough to coat the back of a spoon. Stir in the Dijon mustard, nutmeg, and half of the Parmesan cheese. Taste and adjust salt and pepper as needed.
- Return the cooked chicken, drained pasta, and broccoli to the skillet with the sauce. Toss gently to coat everything evenly. If the sauce appears too thick, add the reserved pasta water, one splash at a time, until the desired creamy consistency is reached.
- Remove from heat. Stir in the remaining Parmesan cheese and fresh parsley. Serve immediately with extra Parmesan sprinkled over the top.