In a bowl, mix together the provolone, ricotta, Parmesan, garlic, and salt and pepper. Set aside.
Bring 1/2 inch of water to a boil in a pot with a steamer basket. Add the spinach, cover, and steam for 1-2 minutes until wilted. Drain and squeeze out excess moisture.
Butter one side of each bread slice with 1 tsp butter.
Layer the spinach, basil, cheesy ricotta mixture, and sun-dried tomatoes between the bread slices.
Cook in a non-stick skillet over medium-low heat for 4-6 minutes per side until golden brown, covering briefly to help melt cheese.
Serve hot!