In a skillet, heat olive oil over medium heat. Add chopped onion and garlic, sauté until soft.

Add chopped spinach and cook until wilted. Remove from heat and let cool.

In a bowl, combine cooled spinach mixture with feta cheese, dill, salt, and pepper.

Preheat the oven to 375°F (190°C).

Lay one sheet of phyllo dough in a greased baking dish, brushing with melted butter. Repeat with several layers.

Spread the filling evenly over the phyllo layers.

Cover with more phyllo sheets, brushing each layer with butter. Tuck edges in to seal.

Cut the top layers into squares for serving.

Bake for 45 minutes or until golden brown.