Chocolate Croissant - Pain Au Chocolat

Ingredients (Makes 18 Croissant)

• 1⁄2 cup milk
• 1⁄3 cup sugar
• 1 tbsp. yeast
• 1 1⁄2 cups plus 2 tbsp. unsalted butter, barely softened; plus 3 tbsp. melted and cooled
• 1 tbsp. salt
• 1 tbsp. powdered milk
• 1 egg, mixed with 1 tbsp. water, for egg wash
• 4 cups flour
• 18 1⁄2"-wide x 3"-long bittersweet chocolate bars