Cheesy Spinach Stuffed Chicken Breasts

Ingredients
For the Chicken Breasts:
3 large chicken breasts, boneless, skinless (1 3/4 to 2 lbs, even-sized pieces)
3/4 tsp salt
1/2 tsp black pepper
1/2 tsp garlic powder
1/2 tsp paprika
1 1/2 Tbsp olive oil
For the Filling:
4 oz cream cheese, cold
1 Tbsp mayonnaise
2 garlic cloves, pressed
1/4 tsp salt
1 1/2 cups baby spinach leaves, chopped
1/4 cup mozzarella cheese
1/4 cup parmesan cheese
Instructions
Preheat oven to 425˚F with a rack in the center. In a mixing bowl, mash together cream cheese, mayo and garlic with a fork then stir in mozzarella, parmesan and chopped spinach leaves until combined.
Lay chicken on a flat surface and cut slit 3/4 of the way through without cutting all the way through. Stuff each chicken breast with 1/4 of the mixture and seal horizontally with a toothpick (make sure the chicken breast can lay flat on the sides for searing.
Season the outside of the chicken breast all over with 3/4 tsp salt, 1/2 tsp pepper, 1/2 tsp garlic powder and 1/2 tsp paprika, or season to taste.
Heat 1 1/2 Tbsp olive oil in an oven-proof pan such as cast iron, or large heavy-bottomed skillet over medium heat. Add chicken and sauté for 4 minutes per side until golden brown on each side.
Flip a second time and immediately transfer skillet to preheated oven. Bake at 425˚F for 10-15 minutes until thermometer inserted into the thickest part of the chicken registers at 165˚F. Rest chicken 5 minutes before slicing. Spoon pan juices over chicken to serve.