Season the chicken breasts with salt and pepper
Heat olive oil in a large skillet over medium heat
Add the chicken breasts to the pan
Cook for about 5–6 minutes per side until golden
Remove chicken from the pan and set aside
Add asparagus and garlic to the same pan
Cook for 3–4 minutes until asparagus becomes tender
Add lemon zest and lemon juice
Return chicken to the pan and cook for 2 more minutes
Add butter if using and let it melt into the sauce
Serve warm