Preheat your oven to 450°F (232°C). This high temp ensures a beautiful sear on the chicken while locking in the juices.

Pat your chicken breasts dry with a paper towel—this helps the seasoning stick. Season both sides generously with sea salt and black pepper.

Using a sharp knife, make a horizontal slit in each breast to create a pocket. Be careful not to cut all the way through.

Place chopped spinach into a microwave-safe bowl. Steam in the microwave for 2–3 minutes until wilted. Alternatively, you can sauté it on the stovetop with a splash of olive oil for 3–5 minutes. Let it cool.

In a mixing bowl, combine softened cream cheese and minced garlic. Mix until smooth. Stir in ½ cup of the shredded mozzarella.

Once the spinach has cooled slightly, squeeze out any excess water (important!) and stir it into the cream cheese mixture.

Divide the spinach filling among the four chicken breasts. Carefully stuff each pocket, then secure with toothpicks placed horizontally to keep the filling from spilling out.

Heat olive oil in a large (at least 12-inch) cast iron or oven-safe skillet over medium-high heat until shimmering.

Sear the stuffed chicken breasts for 4–5 minutes per side, or until golden brown.

Quickly top each chicken breast with 2 tomato slices and the remaining ½ cup mozzarella cheese.

Transfer the skillet to the oven and bake for 15 minutes, or until the internal temperature of the chicken reaches 165°F (74°C). Ensure your thermometer is in the meat, not the filling.

For an extra golden top, broil for 1–2 minutes—optional but worth it.