01 - Set the oven to 375°F and line a large baking sheet with parchment paper.
02 - Heat 2 tablespoons of olive oil in a large skillet over medium heat. Add the diced onion and cook for 2 to 3 minutes until translucent. Stir in the minced garlic and cook for an additional 30 seconds.
03 - Add the chopped spinach to the skillet and cook until wilted and most of the moisture has evaporated, about 4 to 5 minutes. Remove from heat and allow to cool slightly.
04 - In a large mixing bowl, combine the cooked spinach mixture with crumbled feta, ricotta, beaten eggs, dill, parsley, ground nutmeg, black pepper, and salt. Mix thoroughly until well incorporated.
05 - Unroll phyllo sheets, keeping them covered with a damp towel to prevent drying. Take one sheet at a time, brush lightly with melted butter, then fold lengthwise into a strip approximately 3 inches wide.
06 - Place a heaping teaspoon of filling at the bottom of the phyllo strip. Fold the corner over the filling to form a triangle, then continue folding the strip upward, maintaining the triangular shape until the strip is fully folded.
07 - Place the formed triangles closely together in a circular or cluster arrangement on the prepared baking sheet, ensuring they touch but do not overlap.
08 - Brush the triangle tops with the remaining melted butter mixed with 2 tablespoons of olive oil. Sprinkle with sesame and nigella seeds if desired.
09 - Bake in the preheated oven for 22 to 25 minutes until the triangles are golden brown and crisp. Let cool for 5 minutes before serving.