Use a mild extra-virgin olive oil rather than a robust variety to avoid competing with chocolate flavors, and it helps create that signature fudgy, tender crumb without adding greasiness.

Press marshmallows into the cookie dough after 8-10 minutes of baking so they partially sink and melt into the warm chocolate while remaining slightly visible on top for that authentic hot cocoa aesthetic.

Sift the cocoa powder with the flour before mixing to eliminate lumps and ensure even distribution, which intensifies chocolate flavor and prevents dry pockets in your cookies.

Slightly underbake the cookies by removing them 1-2 minutes before the brownie mix package suggests—they'll continue cooking on the hot pan and deliver that perfect melting-in-your-mouth texture.

Allow baked cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack; this resting time allows the chocolate structure to set while staying fudgy, and flavors deepen as they cool slightly.