Preheat oven to 350°F. Line two baking sheets with parchment paper and set them aside.
Cream together the softened butter, light brown sugar, and granulated sugar for 1-2 minutes until light and fluffy. Add in the eggs and vanilla extract and mix until combined.
Add in the flour, cocoa powder, baking soda, salt, and espresso powder. Mix until the dough forms, Fold in the chocolate chips and sliced almonds.
Use a large cookie scoop to scoop out the dough. Take each ball of dough and press a large divot in the center Take a whole marshmallow and press it into the divot. Carefully roll the dough into a ball, leaving only part of the marshmallow showing.
Place the balls of dough about 3-4 inches apart on the prepared baking sheets. Press the tops of the dough down to flatten them a slightly.
Bake the cookies for 14-15 minutes. *If the cookies spread a bit too much, use a spatula to pull in the sides and round them back out. Once baked, allow the cookies to cool for about 5-10 minutes on the baking sheet before carefully transferring them to a cooling rack.