How to Make It
Preheat the oven to 350° and line 3 baking sheets with parchment paper. In a standing electric mixer fitted with the paddle, beat the butter until creamy, 1 minute. Add the granulated sugar and brown sugar and beat at medium speed until light and fluffy, 3 minutes. Beat in the eggs and vanilla. In a bowl, dissolve the baking soda in the hot water and stir into the batter. At low speed, beat in the flour and salt until incorporated. Add the chocolate and beat just to distribute evenly.
Scoop 1 1/2-inch balls of dough onto the lined baking sheets, spacing them 1 1/2 inches apart. Bake in the center of the oven, one baking sheet at a time, for 16 minutes, until golden; shift the baking sheet from front to back halfway through. Let the cookies cool. Serve with the Red Miso Buttercream.