1. Preheat oven to 350°F.
2. Unroll refrigerated Puff Pastry Dough. Cut 1 in. wide strips on each side leaving the middle intact. Each strip should be 2 in. in length. Cut out notches, two each on the bottom and the top of the dough sheet.
3. Dice the ham and rough chop the hard boiled eggs. Set aside.
4. Melt butter in a heavy bottom saucepan or skillet. Add flour and stir with whisk while thickening. Add heated milk to mixture and whisk until milk thickens to a heavy sauce. Turn off heat.
5. Fold eggs into the sauce and let yolk dissolve into sauce. Add ham and herbs.
6. Using a large spoon or ice cream scoop, add egg and ham mixture to the center of the puff pastry, in the uncut section in the middle.
7. Start by folding in the top and bottom of the dough sheet to close the ends. Then slightly stretch strips of dough and fold them by crisscrossing dough, starting at the top and working towards the bottom. The bottom strips can be tucked under at the end.
8. Brush with egg wash and bake for 20 minutes. Let cool slightly before cutting.