Begin by peeling and dicing your Yukon Gold potatoes, ensuring they’re cut into uniform pieces for even cooking. Place them in a large pot of salted boiling water and cook for about 15–20 minutes until tender. Drain the cooked potatoes and let them cool down for a few minutes before proceeding with the filling.

While the potatoes cool, heat a skillet over medium heat and add 2 tablespoons of butter. Once melted, add diced yellow onions with a pinch of salt, sautéing for about 5–7 minutes until the onions become tender and translucent. Once cooked, transfer the onions to a bowl and allow them to cool slightly.

In a mixing bowl, combine the cooled potatoes and sautéed onions. Add in your shredded sharp cheddar cheese, heavy cream, Dijon mustard, and flour, seasoning with kosher salt and freshly cracked black pepper. Mix until everything is well incorporated.

To achieve a beautiful golden crust, crack an egg into a small bowl and whisk it with a splash of water. Set the egg wash aside as you prepare to assemble the pies.

Unroll your thawed puff pastry sheets on a lightly floured surface. Cut the pastry into rectangles, approximately 4x6 inches. Brush the edges with the egg wash, add a spoonful of filling in the center, and fold the pastry over to create a pocket. Crimp the edges with a fork to seal them tightly.

Preheat your oven to 425°F (220°C) while preparing your baking sheets lined with parchment paper. Arrange the assembled hand pies, brush the tops with the remaining egg wash, and cut a few slits on top. Bake for 25-30 minutes until golden brown and filling is bubbling.

Once baked, remove the pies from the oven and let them cool on a wire rack for about 5 minutes. Serve warm for the best flavor experience.