Preheat your oven to 375°F (190°C).

In a large skillet, heat olive oil over medium heat. Add the onion and sauté until translucent, about 5 minutes. Stir in the garlic and cook for another 1-2 minutes until fragrant.

If using fresh spinach, rinse it thoroughly. Once the onions and garlic are ready, add the spinach to the skillet. Cook until wilted (or heat through if using frozen).

In a mixing bowl, combine the sautéed spinach mixture with ricotta, feta, and Parmesan cheeses. Add dill, salt, and pepper.

Gently unfold the phyllo dough sheets and cover with a damp towel. On a clean surface, take one sheet of phyllo and brush it lightly with melted butter. Layer another sheet on top and repeat until you have 3-4 sheets stacked.

Spoon some of your filling along one edge of the phyllo, then fold it over to create a roll. Keep rolling until you form a neat package. Place it seam-side down on a baking sheet.

Repeat with the remaining sheets and filling. Brush the tops with more melted butter for a golden finish.

Bake in the preheated oven for 30-35 minutes, or until golden brown.