Preheat the oven to 350° F. Line 2 baking sheets with parchment paper.

In a mixing bowl, beat together the butter, brown sugar, espresso powder, and vanilla until light and fluffy, about 3-5 minutes. Add the egg, mixing to combine. Then, add the maple and mix to combine.

Add the flour, baking soda, salt, cinnamon, ginger, cardamom, nutmeg, all-spice, and pepper, beating until combined.

Place the sugar in a small bowl.

Roll the dough into tablespoon-size balls (if the dough is too sticky, add 2-4 additional tablespoons flour), then lightly roll through the sugar. Place on the prepared baking sheet, spacing the cookies 2 inches apart.

Bake for 8-10 minutes or until the cookies are just starting to set around the edges. The centers should be a little doughy. Let cool on the pan.

Meanwhile, make the icing. Add the butter to a pot set over medium heat. Allow the butter to brown lightly until it smells toasted, about 2-3 minutes. Remove from the heat. Let cool 5 minutes.

Whisk in the powdered sugar, milk, vanilla bean powder, and flaked sea salt. Immediately spread the icing over the cookies, it will set quickly.