1-Melt butter and chocolate: Melt butter and semi-sweet chocolate together until smooth; set aside to cool slightly.

2-Beat eggs and sugar: Beat eggs with granulated and brown sugar until pale, thick, and frothy.

3-Add chocolate and vanilla: Whisk melted chocolate mixture and vanilla into the egg mixture until glossy and fully combined.

4-Sift dry ingredients: Sift together flour, cocoa powder, salt, and optional espresso powder to remove lumps.

5-Fold in dry ingredients: Gently fold the sifted dry ingredients into the wet mixture until just combined, avoiding overmixing.

6-Chill the dough: Cover and refrigerate the dough for at least 30 minutes to firm up and prevent spreading.

7-Scoop onto baking sheet: Line a baking sheet with parchment, then use a cookie scoop to drop uniform mounds, spacing them a few inches apart.

8-Bake the cookies: Bake at 350°F for 10–12 minutes, until edges are set but centers still look slightly underdone.

9-Cool on the sheet: Let cookies rest on the hot baking sheet for 5 minutes to finish setting, then transfer to a wire rack to cool completely.