Next, prepare the chicken cutlets and keep them warm.
In a large frying pan, add the oil and heat over medium heat for 1 to 2 minutes or just until hot.
Stir in the shallots and garlic and cook for 1 to 1 ½ minutes or until very lightly browned but cooked.
Deglaze with the white wine and add in the fresh sage leaves.
Cook the wine until au sec or almost gone, which takes about 2 to 3 minutes.
Remove the pan from the heat and place it on a cool burner that has not been turned on.
Stir in the cold butter, vigorously swirl the pan in a circle, or whisk it in to emulsify the sauce, making it thick.
Finish the sauce with lemon juice, salt, and pepper, and mix it in.
Drizzle the sauce over the chicken cutlets and serve.
Notes
Make-Ahead: These chicken cutlets and sauce are meant to be eaten as soon as they cook. Keep them warm over a rack on a sheet tray and in the oven at low temperatures (<200°) for 30 minutes before making the sauce.How to Store: If possible, store it in the refrigerator, covered in plastic, and separate from the sauce for up to 3 days. It freezes well, covered individually, for up to 3 months. How to Reheat: Add the desired number of chicken cutlets to a sheet tray lined with parchment paper and bake in the oven at 350° for 8 to 10 minutes or until hot. In the meantime, add the sauce to a small pot with ¼ to 1/3 cup of heavy whipping cream and heat over low heat while constantly whisking until re-emulsified.If the butter sauce breaks and, add 1 to 2 tablespoons of cold whipping cream while vigorously mixing it to help re-emulsify it.Feel free to garnish the dish with optional minced fresh parsley.If you do not drink wine, I recommend using three tablespoons of water mixed with the juice of ½ lemon.