01 -
In a medium bowl, whisk together all-purpose flour, unsweetened cocoa powder, salt, and baking soda until evenly combined.
02 -
In a large mixing bowl, use an electric mixer to cream unsalted butter with granulated sugar until light and fluffy, about 3 to 4 minutes.
03 -
Beat in eggs, one at a time, ensuring each egg is fully mixed before adding the next. Blend in vanilla extract.
04 -
Gradually add the dry mixture to the creamed butter mixture. Mix on low speed until the dough is just combined. Avoid overmixing.
05 -
Cover and refrigerate the dough for at least 1 hour to firm up and prevent excessive spreading during baking.
06 -
Preheat oven to 350°F and line two baking sheets with parchment paper or silicone baking mats.
07 -
Scoop chilled dough with a tablespoon or cookie scoop, rolling each portion into a ball. Arrange on prepared sheets, spacing 2 inches apart. Make a small indent in the center of each with your thumb.
08 -
Spoon about 1 teaspoon marshmallow fluff into each indent and use a toothpick to create a swirl pattern throughout the cookie.
09 -
Bake in preheated oven for 10 to 12 minutes, or until edges are set and centers remain soft. If desired, add extra marshmallow fluff to the top halfway through baking for added texture.
10 -
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to set completely.