Step 1: Prepare the Filling

1. Heat 1 tablespoon of olive oil or butter in a skillet over medium heat.
2. Add the minced garlic and sauté for 30 seconds until fragrant.
3. Add the chopped spinach and cook for 1-2 minutes, stirring occasionally, until wilted. Remove from heat and set aside.

Step 2: Assemble the Sandwich

1. Spread hummus or tzatziki (if using) on one side of each slice of bread.
2. Layer one slice with cooked spinach, sun-dried tomatoes, kalamata olives (if using), crumbled feta, and shredded mozzarella.
3. Top with the second slice of bread, spread side down, to create a sandwich. Repeat for the second sandwich.

Step 3: Grill the Sandwich

1. Heat the remaining olive oil or butter in a skillet over medium heat.
2. Place the sandwiches in the skillet and cook for 3-4 minutes on each side, pressing gently with a spatula, until the bread is golden brown and the cheese is melted.

Step 4: Serve and Enjoy

1. Slice each sandwich in half and serve warm. Pair with a fresh salad or soup for a complete meal.