Preheat oven to 375°F. Line a baking sheet with parchment paper; set aside.

Working on a lightly floured countertop, place one sheet of puff pastry on counter. Spread cubed butter evenly on top and then lay 2nd sheet of puff pastry on top.

Lightly flour the top of the puff pastry and then use a rolling pin to roll dough into a large 15”x20” rectangle. (Tip: Work carefully here as the puff pastry can tear if you are too rough.)

Using a pizza wheel, cut the dough lengthwise to create (2) 15”x10” rectangles. Cut each rectangle into 10 triangles. (The base of each triangle should be ~3”. See photo in post for example.) This will create 20 total triangles.

Make a 1” cut in the middle of each triangle base. Place chopped chocolate bars parallel to the base and then roll the dough, starting with the base, over itself into a tight roll. Place croissants on parchment-lined baking sheet, tip-side down.

Brush the tops of the croissants with the lightly beaten egg wash.

{Optional} Sprinkle the tops of the croissants generously with coarse sugar.

Bake at 375°F for 28-32 minutes, or until tops of croissants are deep golden in color.

Let croissants cool and then dust with powdered sugar immediately before serving.