Smothered Chicken with Creamed Spinach

Season the chicken breasts on both sides with 1/2 teaspoon of the kosher salt and 1/4 teaspoon of the black pepper. Heat 2 tablespoons of the olive oil in a large, oven-safe skillet over medium-high heat. Sear the chicken for 4-5 minutes per side, until a golden-brown crust forms. The chicken will not be cooked through. Transfer the chicken to a clean plate and set aside.
Reduce the heat to medium and add the remaining 1 tablespoon of olive oil to the same skillet. Add the chopped onion and cook for 4-5 minutes, stirring occasionally, until it becomes soft and translucent. Add the minced garlic and cook for 1 more minute until fragrant.
Add the fresh spinach to the skillet in large handfuls, stirring continuously until each batch wilts before adding the next. Cook until all the spinach is wilted and any excess liquid has evaporated, which should take about 5 minutes.
Reduce the heat to low and stir in the cream cheese, heavy cream, Parmesan cheese, the remaining 1/2 teaspoon of salt, the remaining 1/4 teaspoon of pepper, and the nutmeg. Stir continuously until the cream cheese has fully melted and the sauce is smooth and creamy.
Return the seared chicken breasts to the skillet, nestling them into the creamed spinach sauce. Spoon some of the sauce over the top of each chicken breast. Simmer gently for 8-10 minutes, or until the chicken is cooked through and registers 165°F on an instant-read thermometer.