In a skillet, heat olive oil over medium heat. If using garlic, add minced garlic. Sauté spinach for 2-3 minutes until wilted. Remove from heat.

Spread ricotta on one side of each slice of sourdough bread and season with salt and pepper if desired.

On one slice of bread, layer sautéed spinach, chopped sun-dried tomatoes, and shredded mozzarella. Top with the second slice of bread, ricotta side up.

Spread butter or brush olive oil on the outer sides of the sandwich.

Heat a skillet over medium heat and grill the sandwich for 3-4 minutes until golden. Press down gently with a spatula.

Flip the sandwich and grill the other side for another 3-4 minutes until crispy and cheese is melted. Remove from skillet.

Let sit for a minute before slicing in half diagonally. Serve warm.