Chicken Cordon Bleu in Puff Pastry

I love puff pastry!! This chicken was amazing, and juicy!! For the mustard I used a mixture (to taste) of mayo, yellow mustard and white sugar, seems weird but it was very good. I didn’t use all these spices, I just used salt and pepper. The amounts below seem excessive to me, and I like how the chicken ended up just tasting like chicken instead of garlic and onion powder.

4 boneless, skinless chicken breasts
1 salt, to taste
1 pepper, to taste
1 tablespoon garlic powder (didn’t use)
1 tablespoon onion powder (didn’t use)
16 slices swiss cheese (I used 2, not 4 pieces per breast)
½ lb ham, sliced (225 g) (I used one thin slice of prosciutto per breast)
2 sheets puff pastry, thawed if frozen (I had to use the entire 2 sheets for 3 breasts. I guess I don’t like to roll it too thin…)
¼ cup english mustard (60 g) (I used a mixture (to taste) of mayo, yellow mustard and white sugar, seems weird but it was very good.)
1 egg, beaten for wash on puff pastry

Preparation
Sprinkle the chicken breasts with salt, pepper, (not garlic powder, and onion powder,) tossing to coat evenly.
On a cutting board, place a chicken breast between two sheets of plastic wrap and pound until about ½-inch (1 cm) thick with a meat mallet, rolling pin, or heavy pan. (I sliced the chicken in the middle without cutting through and then pounded)
Remove the plastic wrap and place a layer of Swiss cheese, then ham, then one more layer of Swiss cheese.
Evenly roll the chicken, and place onto a new sheet of plastic wrap.
Wrap the chicken in the plastic wrap, twist the excess plastic, and roll the chicken while twisting the sides in to tighten and firm up the roll of chicken cordon bleu. Tie the excess and chill in the fridge to set for 30 minutes.
Preheat oven to 400°F (200°C).
Cut the puff pastry sheets in half and gently roll out width-wise.
Brush the pastry with mustard and place the chicken on to the bottom edge of the pastry.
Tightly roll the chicken in the puff pastry, pinching the seams together to close and folding the sides under the bottom.
Place the chickens rolls on lightly greased cast iron. (14″ pizza pan) and brush all sides with egg wash.
With a fork, score a decorative design onto the surface of the puff pastry.
Sprinkle with salt.
Bake for 35-40 minutes (mine was 40 minutes) or until the puff pastry is a dark golden brown and the internal temperature of the chicken is 165°F (75°C).
Enjoy!

This is the amounts of sugar, mustard and mayo I used.

https://tasty.co/recipe/chicken-cordon-bleu-bake