In a mixing bowl, combine melted butter, chocolate chips, and cocoa powder to create a rich cookie dough. Chill the dough for at least 20 minutes.

Set your oven to 350°F (175°C).

Using a spoon, drop generous dollops of the chilled dough onto a lined baking sheet, leaving space between each cookie.

Place the cookies in the oven and bake for 10-12 minutes or until the edges are set but the centers remain soft.

On a microwave-safe plate, microwave the marshmallows for about 45 seconds until they puff and soften.

Once the marshmallows are warm, stretch them gently and place them over the baked cookies to create the spider web effect. Add googly eyes if desired.