Bring a large pot of salted water to a rolling boil. Add gluten-free fettuccine and cook according to package directions, about 8-10 minutes. Reserve 1/3 cup of pasta water before draining and set aside.

Blend the ingredients for the dairy-free alfredo sauce in a blender for 2-3 minutes until creamy. Taste and adjust flavors if necessary.

In a large skillet, heat olive oil or plant-based butter over medium-high heat. Add chicken, season with sea salt, and cook for 7-10 minutes until browned and cooked through. Transfer chicken to a plate to rest.

In the same skillet, add leeks and broccoli. Sauté for about 3 minutes until vibrant and crisp. Deglaze the skillet with a splash of white wine or chicken stock and cook for an additional 2 minutes.

Reduce heat to low, return chicken to skillet, add drained pasta, and pour in the alfredo sauce. Stir gently and add reserved pasta water to reach desired consistency.

Garnish with freshly chopped parsley or chives and serve immediately.