Heat a tablespoon of olive oil in a skillet over medium heat. Add the minced garlic and sauté until fragrant, about 30 seconds, until garlic is golden and smells inviting.
Add the chopped spinach to the skillet. Stir constantly until wilted and tender, about 2-3 minutes. Season with a pinch of salt and pepper, then remove from heat and set aside.
Place a tortilla on a clean surface and evenly spread the sautéed spinach mixture over half of it, then sprinkle crumbled feta cheese on top.
Fold the tortilla over the filling to create a half-moon shape, pressing gently to seal the edges.
Heat the skillet over medium heat again, then carefully transfer the folded quesadilla onto it. Cook for 3-4 minutes on each side, or until the exterior is golden brown and crispy, and the feta starts to melt.
Use a spatula to flip the quesadilla once the bottom is golden and crispy. Continue cooking until the other side is also golden and the cheese is bubbling inside.
Remove the cooked quesadilla from the skillet and let it rest for a minute. Then, cut into wedges and serve hot, with the cheese gooey and the crispy shell intact.
