Preheat an oven to 375 degrees. Lightly grease baking sheets with olive oil.
Heat 3 tablespoons olive oil in a large skillet over medium heat. Sauté onion, green onions and garlic, until soft and lightly browned. Stir in spinach and parsley, and continue to sauté until spinach is limp, about 2 minutes. Remove from heat and stain excess liquid from the spinach mixture, set aside to cool.
In a medium bowl, mix together eggs, ricotta, and feta. Stir in cooled spinach mixture.
Arrange one sheet of phyllo dough on a clean work surface and brush with olive oil. Cover the remaining phyllo dough with a damp towel. Place a second sheet of phyllo on top and brush with olive oil, then place a third sheet on top. Cut the oiled phyllo lengthwise into four strips.
Place about 1 tablespoon of the spinach mixture on the bottom of each strip. Take the bottom right corner and fold the dough over the filling to make a triangle. Fold the bottom left corner up to make another triangle. Continue folding until all the dough is folded. Arrange the stuffed triangles, seam-side down, on the prepared baking sheets. Lightly brush the triangle with olive oil. Repeat with the remaining phyllo dough and spinach filling.
Bake in the preheated oven until golden brown, about 20 minutes. Serve warm with Tzatziki Sauce.