In a large bowl (or food processor), whisk together flour, salt, black pepper, oregano, and garlic powder.

Cut in the cold, cubed butter using a pastry blender or your fingertips (or pulse in a food processor) until the mixture resembles coarse crumbs with some pea-sized pieces of butter remaining.

Stir in the grated Parmesan cheese.

Gradually add ice water, 1 tablespoon at a time, mixing until the dough just comes together. Be careful not to overmix. Form the dough into a disc, wrap in plastic, and refrigerate for 20 minutes.

Preheat oven to 375°F (190°C). Line two baking sheets with parchment paper.

On a lightly floured surface, roll out the chilled dough to about 1/8-inch thickness.

Using a 2-inch round cookie cutter, cut out circles. Carefully transfer cookies to the prepared baking sheets, leaving about 1 inch between them. Reroll scraps as needed.

Bake for 12-15 minutes, or until edges are lightly golden and cookies are firm.

Transfer cookies to a wire rack to cool completely.

In a medium bowl, combine softened cream cheese, finely crumbled feta cheese, minced chives, minced dill, black pepper, and optional red pepper flakes.

Beat with an electric mixer on medium speed until smooth and well combined.

Once the cookies are completely cool, spread about 1/2 to 1 teaspoon of the feta and herb filling on the flat side of one cookie.

Top with another cookie, pressing gently to form a sandwich.

Repeat with the remaining cookies and filling.