Step 1: Preheat your oven to 350°F (175°C) to ensure even baking.
Step 2: In a medium saucepan over low heat, combine the unsalted butter and unsweetened baking chocolate. Stir continuously until melted and smooth. Remove from heat and let cool slightly.
Step 3: In a mixing bowl, whisk together the granulated sugar, cocoa powder, vanilla extract, salt, and baking soda. Add the melted chocolate mixture and mix until well combined. Beat in the egg until smooth and glossy.
Step 4: Gradually add the all-purpose flour to the chocolate mixture, mixing just until combined. Be careful not to overmix!
Step 5: Gently fold in the chocolate chips or chunks.
Step 6: Using a cookie scoop or tablespoon, drop balls of dough onto a parchment-lined baking sheet, leaving space for spreading.
Step 7: Bake for 10-12 minutes, or until the edges look set and the tops are slightly cracked. The centers may look underbaked.
Step 8: Allow cookies to cool on the baking sheet for about 5 minutes before transferring to a wire rack to cool completely.
