Add the spinach, dill, parsley, feta cheese, and eggs and season with salt and pepper. Mix together until well combined.
Preheat the oven to 350F and line a large baking sheet with parchment (skip preheating the oven if you are freezing the spanikopita for future use).
Taking 1 sheet of FILO at a time (cover the filo that isn't being used with a clean slightly damp towel to prevent it from drying out), lay it out flat on a clean surface and brush lightly with the melted butter or olive oil using a pastry brush. Fold the sheet in half length ways. Place 2-3 tablespoons of filling in the middle of the lower 1/4 of the pastry and roll up by folding it forward until it is folded half way up the sheet. Fold in the sides (like a burrito) and continue to fold the parcel forward until no more FILO is left. Place seam side down on the prepared baking sheet, and repeat until all of the filling is used up. You can freeze the spanikopitas at this stage if desired (freeze on baking sheet and transfer to an air tight container).
*squeeze out as much water as possible by pressing in a clean cloth or fine sieve