Preheat the oven to 375 degrees F and lightly oil an 8 by 8 inch baking dish.
Heat 1 tablespoon of the olive oil in a large skillet over medium heat. Add the onion and cook until soft, about 5 minutes.
Stir in the garlic and cook for 1 minute more. Add the spinach in batches and cook until wilted. Remove from heat and let cool slightly.
In a mixing bowl, beat the eggs. Stir in the crumbled feta, dill, salt, and pepper. Mix in the cooled spinach.
Lay one phyllo sheet in the baking dish and brush lightly with olive oil. Repeat with four more sheets, brushing each layer.
Spread the spinach filling evenly over the phyllo base.
Top with the remaining five phyllo sheets, brushing each with olive oil. Tuck the edges down around the sides.
Score the top layers into squares with a sharp knife. Bake for 35 to 40 minutes until the crust is golden and crisp. Cool for 10 minutes before slicing.