• Preheat oven to 350°F (180°C). Line rimmed baking sheets with parchment paper.

Using an Ankarsrum Mixer:

• Assemble Ankarsrum mixer with stainless steel bowl. Place dough knife in smaller hole, and position dough roller just off side of bowl. Add butter; slowly increase mixer speed to medium-high (6 o’clock), and beat until creamy, about 1 minute, using scraper to help move butter around. (Butter might stick to the roller in the beginning.) Slowly add sugars, beating until well combined and lightened in color, about 3 minutes. Add egg, egg yolk, and vanilla, beating until combined.
• In a medium bowl, whisk together flour, baking powder, salt, and baking soda. With mixer on lowest speed (12 o’clock), gradually add flour mixture to butter mixture. Move roller to 1 inch away from side of bowl, and increase mixer speed to medium-low (2 o’clock), beating until combined.
• Remove bowl from mixer. Fold chocolate chips and chopped chocolate into dough with a rubber spatula until combined. Using a 3-tablespoon springloaded scoop, scoop dough (about 53 grams each), and place at least 2 inches apart on prepared pans.
• Bake until edges are golden brown and set, 10 to 12 minutes. Garnish with dark chocolate dust and crumbs, if desired. Let cool on pans for 10 minutes. Remove from pans, and let cool completely on a wire rack. Store in an airtight container for up to 1 week.

Using a Conventional Mixer:

• In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugars at medium speed until fluffy and lightened in color, 2 to 3 minutes, stopping to scrape sides of bowl. Add egg and egg yolk, beating until well combined. Beat in vanilla.
• In a medium bowl, whisk together flour, baking powder, salt, and baking soda. With mixer on low speed, gradually add flour mixture to butter mixture, beating until just combined.
• Remove bowl from mixer. Fold chocolate chips and chopped chocolate into dough with a rubber spatula until combined. 
• Bake until edges are golden brown and set, 10 to 12 minutes. Garnish with dark chocolate dust and crumbs, if desired. Let cool on pans for 10 minutes. Remove from pans, and let cool completely on a wire rack. Store in an airtight container for up to 1 week.