Between two pieces of plastic wrap, pound the halved chicken breasts to an even thickness (about ¼ inch). Season all over with Dijon mustard, ½ teaspoon Italian seasoning, ½ teaspoon garlic powder, ½ teaspoon onion powder, ½ teaspoon salt, and black pepper, to taste. Make sure the chicken is fully coated on both sides.
Dredge each piece of chicken in flour and shake off any excess.
In a large skillet, add the asparagus with ¼ water, cover and cook over medium heat to steam 2 to 3 minutes, until crisp tender. Remove and set aside.
In the same skillet, heat the butter over medium-high heat. Add the chicken and cook for about 4 to 5 minutes per side, or until each piece is cooked through and has a golden-brown crust. Remove and set aside.
Add chicken bone broth, half-and-half, remaining Italian seasoning, ¼ teaspoon salt, garlic powder and onion powder to the pan. Reduce by half over medium-low heat, until it thickens, thick enough that it coats the back of a spoon.
Add the lemon juice and nestle the cooked chicken into the sauce and simmer for a few minutes, until heated through. Finish with lemon zest.
Serve with asparagus, drizzling the sauce over the chicken.