Combine 2 cups flour and 1/2 tsp salt in a large bowl. Add the cold, cubed butter and, using a pastry cutter or fingertips, cut the butter into the flour until the mixture resembles coarse crumbs with pea-sized butter pieces remaining.

Add water and chill

Sprinkle 4 tablespoons cold water over the mixture and gently toss with a fork until the dough just comes together when pressed (add up to 1 additional tablespoon if very dry). Gather into a disk, wrap in plastic, and chill in the refrigerator for 30 minutes.

Prepare egg wash

About 15 minutes before rolling, whisk 1 egg with 1 teaspoon milk in a small bowl and set aside.

Filling

Prepare cheese mixture

In a medium bowl, beat together the 4 oz softened cream cheese and 1 tablespoon Dijon mustard until smooth. Fold in the grated cheddar (1.5 cups), chopped chives (2 tablespoons), 1/4 tsp black pepper, and the optional 1 teaspoon honey or maple syrup if using. Taste and adjust seasoning.

Assemble ham slices

Lay out the 8 oz of thinly sliced ham on a cutting board and, if slices are large, fold or stack so they will fit neatly on pastry rectangles.

Assembling & Baking

Roll out dough

Preheat the oven to 400°F (200°C). Lightly flour a work surface with 1/4 cup flour. Roll the chilled dough into a rectangle about 12 x 10 inches and approximately 1/8–1/4 inch thick. Trim edges into a clean rectangle. Cut the dough into 6 equal rectangles (about 4 x 3.3 inches each) for individual pastries.

Fill pastries

On half of the rectangles, spread about 2 heaping tablespoons of the cheese mixture, leaving a 1/2-inch border. Top the cheese mixture with a portion of ham (about 1.25 oz per pastry, or enough to cover the cheese). Brush the borders with egg wash to help seal.

Seal and egg wash

Place the remaining pastry rectangles over the filled ones and press the edges together with your fingers, then crimp with a fork to seal. Trim any excess. Brush the tops with the reserved egg wash and, if desired, sprinkle with a pinch of coarse sea salt. Using a sharp knife, make a small 1/2-inch slit in the center of each pastry to let steam escape.

Bake

Place pastries on a parchment-lined baking sheet about 1 inch apart. Bake in the preheated 400°F (200°C) oven for 18–22 minutes, or until golden brown and puffed and the filling is hot. Rotate the pan halfway through baking for even color.

Cool and serve

Remove from oven and let cool on the baking sheet for 5 minutes, then transfer to a wire rack for another 5 minutes. Serve warm or at room temperature. These pastries keep well for up to 2 days refrigerated and can be reheated at 325°F (160°C) for 8–10 minutes.