Start by wilting the baby spinach in a pan over medium-high heat with the minced garlic clove and about 1 tablespoon of water. Cook until the spinach is dark green and soft, with no water remaining.
Once the spinach is cooked, strain it well and chop it roughly.
In a large mixing bowl, add the crumbled Feta cheese, the Ricotta cheese, the chopped parsley, the fresh or dried mint, and the garlicky spinach (once it's cooled down to room temperature). Mix well, season with salt and pepper to taste. You can also add some chili pepper here if you'd like.
Preheat the oven to 200C and line a baking tray with a sheet of parchment paper.
Cut each sheet of Yufka dough in half to make a smaller triangle. Brush each sheet with a little bit of water to make sure the dough is slightly moist and not dry.
Add about a tablespoon of the filling at the longer end of the triangle, then roll the triangle into a tube.
Quickly whisk the egg in a small bowl with a fork. Using your finger, brush the tip of the triangle with the egg, using it as glue to close the tube. Place the cigar on the baking tray.
Repeat until all of the filling is gone and you've used up all of the dough.
Brush each cigar with the remaining egg wash, and then sprinkle with nigella seeds.
Bake for approximately 20 minutes or until the cigars are golden brown.