Add butter to a small saucepan and cook over medium heat, stirring constantly, until melted. Alternately, melt in the microwave. (Optional step for extra caramel-y flavor: Brown the butter! Keep cooking after the butter has melted. The butter will foam and bubble as it cooks. Once the liquid becomes golden brown remove from the heat and add to the bowl of a stand mixer and let cool for 2 minutes. Use 1 additional tablespoon of butter if browning it to account for evaporation.)
Add the brown sugar, white sugar, and espresso powder to the butter and beat until well combined.
Beat in the vanilla and egg until just combined.
Gradually pour in the flour, baking soda, and salt and mix until just combined.
Stir in the chocolate chips by hand, reserving a few to press onto the tops of the cookie dough, if desired.
Portion into 9 large balls of dough and place on a large baking sheet. Dot the tops with the remaining chocolate chips.
Bake for 11 minutes exactly. Cookies will still be slightly underdone when you remove them from the oven. Do not overbake. Let sit on baking sheet for 5 minutes before removing to a cooling rack or eating.
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Notes
When I first created this recipe I always browned the butter first. Now I've gotten more lazy and don't bother. I don't notice a huge difference in taste and it saves about 5 minutes to skip the browning step. Either way, these cookies are still our favorite and we still make them every. single. week. Sometimes multiple times. ;)This recipe doesn't always turn out well when doubling for some reason. We tend to just make one batch at a time.The espresso powder is completely optional. It just adds a little depth of flavor to the cookie, but doesn't make it taste like coffee at all. Totally fine to skip it if you prefer.