In a large mixing bowl, combine all-purpose flour, baking powder, and kosher salt until well blended. Cut in the cold unsalted butter using a pastry cutter or your fingers until the mixture resembles small peas.

Wrap the dough tightly in plastic wrap and place it in the refrigerator for at least 1 hour.

Preheat your oven to 400°F (200°C). Line two baking sheets with parchment paper.

On a floured surface, roll out the chilled dough into a 16-inch square, ensuring it’s about 1/8 inch thick. Cut the dough into 8 smaller squares.

On one side of each dough square, layer sliced deli ham and pieces of brie cheese. Sprinkle chopped chives, a dash of fresh cracked pepper, and a pinch of salt for added flavor.

Brush the edges of each filled square with the beaten egg wash mixture to help seal the Ham and Brie Pop Tarts. Fold the opposite side over the filling to create a pocket, then press the edges together firmly.

Place the prepared pop tarts on the lined baking sheets and brush the tops with the remaining egg wash. Bake in the preheated oven for 15 minutes, then rotate the sheets and bake for an additional 10-15 minutes, or until golden brown.

Once baked, let your Ham and Brie Pop Tarts cool on the baking sheets for about 10 minutes. Garnish with fresh chives and serve warm or at room temperature.