Brownie Cookies

Preheat the oven to 350℉ (177℃). Prepare baking sheet pans with silicone baking mats or parchment paper.
In a microwave-safe bowl, combine the semisweet chocolate chips and unsalted butter. Heat in the microwave in 30 second intervals, stirring in between each interval until the chocolate is melted and smooth. Set aside to cool while completing the next step.
In the bowl of a stand mixer fitted with a whisk attachment or in a large mixing bowl with an electric hand mixer, whip the brown sugar, granulated sugar, and eggs for about 3 minutes until light and pale. Add in the vanilla extract and instant espresso powder and mix on low until combined.
While mixing on low speed, slowly pour in the melted chocolate to temper the egg mixture. Continue to mix on low until the chocolate is well combined.
If you are using a stand mixer, switch to a paddle attachment. Add the all-purpose flour, dark cocoa powder, and salt. Mix on low speed just until the brownie batter is combined and smooth. Scrape the sides and bottom of the bowl. Do not over mix the brownie batter.
Portion the brownie batter with a large cookie scoop (3 tablespoons) and place on the prepared baking sheet pans allowing room for spreading. Sprinkle with flaky sea salt before baking, if desired.
Bake the cookies for approximately 13 to 14 minutes until the edges of the cookies are set and the centers are soft. Cool the cookies on the pan for 5 minutes and then transfer to a wire rack to cool completely.