01 - Preheat oven to 375°F (190°C). Line a baking sheet with parchment paper and set aside.
02 - In a mixing bowl, combine the chopped artichoke hearts, sliced green onions, grated Graviera cheese, Greek yogurt, chopped dill, parsley, lemon zest, black pepper, and salt. Stir until all ingredients are evenly distributed.
03 - Lay one sheet of filo pastry on a clean work surface. Keep remaining sheets covered with a damp kitchen towel to prevent them from drying out. Lightly brush the sheet with melted butter. Place a second sheet on top and brush again with butter. Repeat with a third sheet to create a stack of three buttered layers.
04 - Using a sharp knife, cut the layered filo stack lengthwise into three equal-width strips.
05 - Place approximately 1 tablespoon of the filling near the bottom of each strip. Fold one corner of the filo over the filling to form a triangle. Continue folding the strip upward in a triangular pattern, keeping the filling enclosed, until the entire strip is folded.
06 - Place each folded triangle seam-side down on the prepared baking sheet. Repeat the layering, cutting, filling, and folding process with the remaining filo sheets and filling to yield 12 puffs total.
07 - Brush the tops of the assembled puffs with melted butter or egg wash for deeper browning. Bake for 20 to 25 minutes until the pastry is golden brown and crisp.
08 - Allow the puffs to cool slightly on the baking sheet before transferring to a serving platter. Serve warm.