Preheat your oven to 375 degrees F. Lightly grease a baking sheet or line it with parchment paper.
Gently unroll the thawed phyllo dough. Keep the sheets covered with a slightly damp kitchen towel while you work to prevent them from drying out.
In a medium bowl, combine the dry spinach, crumbled feta cheese, beaten egg, Parmesan cheese, oregano, pepper, and dill, if using. Mix gently until just combined.
Lay one sheet of phyllo dough flat on your work surface. Brush the entire surface lightly with olive oil.
Place a second sheet of phyllo dough directly on top of the first. Brush this second sheet lightly with olive oil.
Cut the stacked phyllo sheets into 9 equal squares.
Place about 1 teaspoon of the spinach and feta filling onto the center of each square.
Fold the phyllo square into a triangle shape, pressing the edges firmly to seal the filling inside. You can crimp the edges with a fork for extra security.
Place the sealed crisps onto the prepared baking sheet. Repeat the process with the remaining phyllo sheets and filling until all the mixture is used. You should have about 30-36 crisps.
Brush the tops of the assembled crisps lightly with any remaining olive oil.
Bake for 12 to 15 minutes, or until the phyllo is golden brown and crisp.
Remove from the oven and let cool slightly before serving. These are great as make ahead appetizers Mediterranean.
Notes
Squeezing the water out of the spinach is the most important step; excess moisture will make your crisps soggy. Use a clean kitchen towel or paper towels to press hard.
If you want a richer flavor, substitute melted butter for olive oil when brushing the phyllo layers.
These freeze well. Assemble them completely, place them on a baking sheet to freeze solid, then transfer to a freezer bag. Bake directly from frozen, adding 5-7 minutes to the baking time.