Wash and roughly chop the fresh spinach leaves, then salt generously and let them sit for 30 minutes to draw out excess moisture.

In a skillet, heat olive oil over medium heat and sauté diced yellow onion until golden brown, then add minced garlic and cook for one minute.

In a large mixing bowl, combine the drained spinach, onion mixture, ricotta, crumbled feta, herbs, and beaten eggs, seasoning with salt and pepper.

Preheat the oven to 350°F (175°C).

Brush a baking dish with melted butter or olive oil, layer 6-8 sheets of phyllo dough, brushing each one, then spread the spinach filling evenly.

Cover with remaining phyllo sheets, brushing and scoring as you go, then bake in the preheated oven for 45-50 minutes until golden brown.

Allow cooling for about 10 minutes before slicing and serving.