Step 1

Preheat the oven to 450 degrees F (232 degrees C). Line a baking sheet or pan with parchment paper or foil (or use a stoneware pan that doesn't stick).

Step 2

Fill a large bowl with water and a couple tablespoons of sea salt. Place the chicken breasts in the water, submerging fully. Brine for at least 10 minutes.

Step 3

Meanwhile, steam the spinach in the microwave for 2-3 minutes, or on the stove for 3-5 minutes, until wilted. When the spinach is cool enough to handle, squeeze over the sink to release as much water as possible. Place back into the bowl.

Step 4

Stir the garlic and 2 oz shredded mozzarella (half of the total amount) into the spinach. Heat the cream cheese until easy to stir, then mix that in.

Step 5

Remove the chicken from the water and pat dry. Place onto the prepared baking pan. Cut a slit in each chicken breast horizontally, creating a pocket.

Step 6

Stuff the spinach mixture into each pocket in the chicken. Sprinkle lightly with sea salt and black pepper.

Step 7

Top each piece of chicken with 2 tomato slices and 1/2 oz shredded mozzarella.

Step 8

Bake for 16-20 minutes, until the chicken is cooked through. (If the cheese starts to brown sooner, you can tent the top with foil and continue baking.)