Creating Spinach and Feta Quesadillas is an absolute breeze if you follow these steps:

1. Sauté Vegetables: Heat olive oil in a skillet over medium heat. Add diced onion and cook until softened, about 3 minutes. Stir in minced garlic and cook for an additional minute.
2. Add Spinach: Toss in fresh spinach and sauté until wilted. Season with salt and pepper to taste. Remove the skillet from heat and let the mixture cool slightly.
3. Combine Cheese: In a bowl, mix together the crumbled feta cheese and shredded mozzarella. Stir in the sautéed spinach and onion mixture until evenly combined.
4. Assemble Quesadillas: Place one tortilla in the skillet and spread a generous portion of the spinach and cheese mixture on half of it. Fold the tortilla over to create a half-moon shape.
5. Cook Quesadilla: Cook the quesadilla on medium heat for about 3-4 minutes, or until the bottom is golden brown. Carefully flip with a spatula, and cook the other side until it is golden and the cheese is melted.
6. Repeat: Remove the cooked quesadilla from the skillet and keep warm. Repeat the process with the remaining tortillas and filling mixture.
7. Slice and Serve: Once all quesadillas are cooked, slice them into wedges for serving.

These clear and simple instructions will guide you in crafting this tasty lunch with ease.