Preheat your oven to 375°F (190°C).
Butterfly the chicken breasts by making a lengthwise cut through the center of each breast, being careful not to cut all the way through. Open up the chicken breasts like a book and gently pound them to an even thickness.
In a skillet, heat the olive oil over medium heat. Add the minced garlic and sauté for about 1 minute, or until fragrant. Add the chopped spinach and cook until wilted, approximately 2-3 minutes. Remove from heat and let it cool slightly.
In a mixing bowl, combine the ricotta cheese, sautéed spinach, grated Parmesan cheese, dried oregano, dried basil, salt, and black pepper.
Spoon the spinach and ricotta mixture onto one side of each butterflied chicken breast. Fold the other side on top, and secure the edges with toothpicks to prevent them from opening during the cooking process.
Place the stuffed chicken breasts in a greased baking dish and bake in the preheated oven for about 25-30 minutes or until the chicken is cooked through and the juices run clear.
Once fully cooked, remove the toothpicks and let the chicken rest for a few minutes before serving.