Mom's Ham & Cheese Puffs

Step 1 -Preheat the oven to 400 degrees F.

Step 2 -Line a large baking sheet with parchment paper.

Step 3 -Cut each of the puff pastry sheets into 4 (5-inch) squares, evenly space them apart on the prepared baking sheet, and set them in the refrigerator.

Step 4 -In a saucepan over medium heat, melt the butter.

Step 5 -Add the flour and the salt to the melted butter and cook, while stirring frequently, until the raw flour smell disappears, about 1 minute.

Step 6 -Slowly add the milk to the flour mixture, while whisking constantly, until incorporated.

Step 7 -Continue to cook the milk mixture, while whisking constantly, until it is smooth and boiling.

Step 8 -Reduce the heat to low.

Step 9 -Simmer the milk mixture, while stirring occasionally, until it begins to thicken into a sauce.

Step 10 -Add the pepper to the sauce mixture and stir to combine.

Step 11 -Add the spinach to the sauce mixture and cook, while stirring gently, until wilted, about 1 minute.

Step 12 -Add the ham and 1 cup of the Swiss cheese to the sauce mixture and stir to combine.

Step 13 -Transfer the saucepan from the heat.

Step 14 -Transfer the baking sheet from the refrigerator.

Step 15 -Top each of the puff pastry squares with 1 heaping spoonful of the ham mixture.

Step 16 -Sprinkle the puff pastry squares with the remaining Swiss cheese.

Step 17 -Fold the corners of each of the squares up, creating small, bowl-like structures with the filling inside. It is okay if some of the filling shows through.

Step 18 -Brush the edges of the pastries with the beaten egg white, making sure to coat them evenly.

Step 19 -Bake until the pastries are puffed and golden, about 18-20 minutes.

Step 20 -Serve.