Season chicken with Italian seasoning, crushed red pepper, salt & pepper. Add 1 tablespoon olive oil to a large skillet over medium heat. Add chicken to the pan and cook for 5-6 minutes per side. Remove from skillet and set aside.
Add butter, onion, and asparagus to the skillet and cook for 2-3 minutes, or until just tender. Add the garlic and cook for just under a minute.
Add heavy cream, lemon juice, and parmesan cheese; stir to combine. Return chicken to the pan and simmer 3-4 minutes or until the sauce has thickened. Taste and adjust salt & pepper if needed. If the sauce is too thick, add ¼ cup water, chicken stock or broth.
