Preheat oven to 375°F (190°C) and line a baking sheet with parchment paper.

Heat 2 tablespoons olive oil in a large skillet over medium heat. Add chopped onions and cook until softened, about 4 minutes.

Add minced garlic and cook for 1 minute until fragrant.

Add fresh spinach in batches, stirring until completely wilted, about 5-6 minutes. Remove from heat.

Transfer spinach mixture to a colander and press out excess liquid. Let cool for 10 minutes.

In a large bowl, combine cooled spinach mixture, crumbled feta cheese, beaten eggs, fresh dill, salt, and black pepper. Mix thoroughly.

Unroll phyllo dough and cut sheets lengthwise into 3-inch wide strips. Keep covered with damp towel to prevent drying.

Take one phyllo strip and brush lightly with melted butter or olive oil.

Place 1 tablespoon of spinach filling at one end of the strip.

Fold one corner over the filling to form a triangle, then continue folding in triangular pattern along the strip.

Place seam-side down on prepared baking sheet. Repeat with remaining phyllo and filling.

Brush tops of triangles with melted butter or olive oil.

Bake for 18-20 minutes until golden brown and crispy.

Remove from oven and let cool for 5 minutes before serving.