Season your chicken with the lemon pepper seasoning and rub it on all sides.
Heat your oil and butter together in a large skillet over medium heat.
Once hot, cook the chicken breasts until golden brown and no longer pink on the inside or until a meat thermometer in the center reads 165 degrees F.
Depending on the size of the breasts, this is usually about 4 minutes per side.
Set your cooked chicken aside and cover to keep warm.
In the same preheated skillet add your minced garlic and cook for 30 seconds stirring frequently.
Add the broth to deglaze your skillet by allowing it to bubble while continuously stirring with a wooden spatula for a minute or so.
Meanwhile, in a small bowl whisk your milk together with the cornstarch/flour until smooth.
Add this milk mixture to the skillet and stir to combine.
Add in the spinach, lemon zest, and lemon juice then simmer over low heat until the spinach is wilted but still bright green, just a minute or two.
Return your chicken to the hot skillet and garnish with lemon slices and freshly chopped parsley.
To serve, spoon some of your creamy spinach sauce over each chicken breast.