Preheat the oven to 350°F.

Place a skillet over medium-high heat. Sear the ham slices for about 1 to 2 minutes per side, until browned and slightly crispy. Remove from the pan and let cool slightly on a paper towel. This will prevent the ham from melting the dough.

Unroll the crescent roll dough onto a baking sheet and separate it into triangles along the perforated lines.

Place a half-slice of Swiss cheese on the wide end of the triangle. Place the cooled ham on top of the cheese. The ham and cheese should fit neatly on the dough; if either one is too long, fold or cut it to fit the dough.

Starting at the wide end with the filling, gently roll the dough toward the pointed tip.

Make sure the crescent rolls are adequately spaced on the baking sheet so that they do not touch one another. The pointed tip of the dough should be tucked underneath each roll to prevent them from unrolling during baking.

Combine the egg and water in a small bowl and beat with a fork or small whisk until well combined. Brush the egg wash over the crescent rolls.

Bake for 12 to 17 minutes, or until the tops are golden brown. Let cool for 5 to 10 minutes before eating, as the cheese inside will be extremely hot.