In a frying pan, heat 1 tablespoon of olive oil over medium heat. Sauté the chopped onion until translucent, about 3–4 minutes. Add the minced garlic and cook for another 1 minute until fragrant. Remove from heat and let cool slightly.
In a mixing bowl, combine the chopped spinach, crumbled feta cheese, sautéed onion and garlic, egg, dill, salt, and pepper. Mix thoroughly until all ingredients are well incorporated.
For each patty, lay out a sheet of phyllo dough on a clean surface. Brush lightly with olive oil before adding another sheet on top. Place a generous tablespoon of the spinach-feta mixture in the middle of the dough.
Fold the edges of the dough over the filling to create a rectangular or triangular patty. Press down gently to seal. Repeat with the remaining dough and filling.
Preheat the oven to 375°F (190°C). Line a baking sheet with parchment paper or lightly grease it with olive oil.
Place the patties on the prepared baking sheet and brush the tops with olive oil for a golden finish.
Bake in the preheated oven for 20–25 minutes, or until the patties are golden brown and crispy.
Remove from the oven and allow to cool for a few minutes before serving.