Start by preheating your oven to 350°F (175°C). Line your cookie sheet with parchment paper. This will not only make cleanup easier but also help prevent the cookies from sticking.

In a medium-sized bowl, combine flour, cocoa powder, baking soda, espresso powder, and sea salt. Whisk them together until they are well coupled. This simple mix ensures that all the flavors spread evenly throughout your dough.

In another large bowl, take the stick of unsalted butter and the granulated sugar. With an electric mixer, beat them together until the mixture is light and fluffy. This process usually takes about 2-3 minutes, mixing makes a world of difference in the final texture.

Now it’s time to add two eggs and the pure vanilla extract. Once incorporated, beat the mixture until fluffy again. The eggs help the cookies rise and provide structure.

Gradually add the flour mixture to the wet ingredients. Mix at a low speed to avoid a flour explosion. Once everything is combined, fold in the chopped chocolate, walnuts, and half of the mini marshmallows and graham crackers. The batter should be thick and delicious!

Use a cookie scoop or two spoons to drop rounded tablespoons of dough onto your prepared baking sheet. Leave enough space between each dollop—about 2 inches should do. They’ll spread out during baking.

Take the remaining mini marshmallows and graham cracker bits, sprinkle them generously on top of each cookie mound. This not only looks fabulous but also enhances that classic s’more experience.

Bake the cookies in your preheated oven for 10-12 minutes. Keep an eye on them! The edges will settle while the centers look slightly undercooked. That's how you want them!

Once baked, remove the cookies from the oven and let them rest on the baking sheet for about 5 minutes. This helps them firm up. Transfer them to a wire rack to cool completely.