Preheat your oven to 190°C (375°F).

Heat butter in a small pan over medium heat, add minced garlic and cook for 30 seconds until fragrant. Add chopped spinach and sauté for 2-3 minutes until wilted. Remove from heat and let cool slightly.

In a bowl, combine the wilted spinach, goat cheese, and half of the shredded mozzarella. Mix until well combined.

Using a sharp knife, cut a deep horizontal pocket into each chicken breast, being careful not to cut all the way through.

Season the inside and outside of each chicken breast with salt, pepper, smoked paprika, and Italian herbs.

Divide the cheese and spinach filling evenly among the four chicken breasts, stuffing it into the pockets. Secure the openings with wooden toothpicks.

Heat olive oil in an oven-safe skillet over medium-high heat. Sear the stuffed chicken breasts for 3-4 minutes per side until golden brown.

Transfer the skillet to the preheated oven and bake for 18-22 minutes, or until the internal temperature reaches 74°C (165°F) when measured with a meat thermometer at the thickest part.

Remove from oven, top each chicken breast with remaining mozzarella, and return to oven for 2-3 minutes until cheese is melted and bubbly.

Remove toothpicks, let rest for 5 minutes before serving. Serve alongside fresh spring salad or steamed vegetables.