1. Prepare the Oven and Baking Sheet: Getting Ready to Bake

1. Preheat Oven: Preheat your oven to 375°F (190°C).
2. Line Baking Sheet: Line a baking sheet with parchment paper. This will prevent the pinwheels from sticking and make cleanup much easier.

2. Prepare the Crescent Roll Dough: Creating the Base

1. Unroll Dough: Open the can of crescent roll dough and carefully unroll it onto a clean, lightly floured surface.
2. Press Seams: Gently press the seams of the dough together to form a single, large rectangle. You can use your fingers or a rolling pin to help seal the perforations.

3. Add Mustard (Optional): A Touch of Tangy Flavor

1. Spread Mustard: If using, spread the Dijon mustard evenly over the surface of the dough, leaving a small border around the edges.

4. Layer Ham and Cheese: Building the Savory Filling

1. Layer Ham: Arrange the ham slices in an even layer over the dough, covering the entire surface (except for the border if you used mustard).
2. Layer Cheese: Top the ham with the Swiss cheese slices, creating an even layer.

5. Roll Up the Dough: Forming the Pinwheel Log

1. Start Rolling: Starting from one of the long edges, tightly roll up the dough into a log, jelly-roll style.
2. Seal Edge: Pinch the edge of the dough to seal the log closed.

6. Slice into Pinwheels: Creating Individual Portions

1. Slice: Using a sharp knife or a serrated knife, slice the log into 1-inch thick pinwheels.
   • Tip: For cleaner cuts, you can chill the log in the refrigerator for 10-15 minutes before slicing.

7. Arrange and Prepare for Baking: Adding the Finishing Touches

1. Place on Baking Sheet: Arrange the pinwheels on the prepared baking sheet, cut-side down, leaving a little space between each one.
2. Brush with Butter: Brush the tops of the pinwheels with the melted butter.
3. Sprinkle with Poppy Seeds (Optional): If desired, sprinkle the tops of the pinwheels with poppy seeds.

8. Bake to Golden Brown: Achieving Flaky Perfection

1. Bake: Bake in the preheated oven for 12-15 minutes.
   • Check for Doneness: The pinwheels are done when they are golden brown on top and the cheese is melted and bubbly.
2. Cool Slightly: Remove the baking sheet from the oven and let the pinwheels cool for a few minutes before serving.

9. Serve and Enjoy: A Delicious and Easy Treat

1. Serve Warm: These Hot Ham and Cheese Pinwheels are best served warm, when the cheese is gooey and the pastry is flaky.