Place butter in a large heatproof bowl set over (but not touching) simmering water; dip a pastry brush in the melted butter and use it to grease the bottom and sides of an 8 x 8-inch baking pan. Add the chocolate to the melted butter and stir frequently until chocolate is melted. Remove bowl from heat; let cool about 10 minutes.

Place the dates and the hot water in a medium the bowl and allow to soak for at least 10 minutes while you prepare everything else.

Preheat the oven to 350 degrees. Line the baking pan with parchment paper, leaving a 1-inch overhang on two sides. Set aside.

Transfer the dates and water to a food processor fitted with the metal blade and process until a smooth paste forms. Add the palm sugar and process until smooth. Alternately you can do this in the bowl of a stand mixer and beat with the paddle attachment. However, the food processor will make the date paste much smoother.

Add the date-sugar mixture to the butter and chocolate mixture and blend well. Add the eggs one at a time, whisking until smooth after each addition. Whisk in vanilla.

Stir in flour, salt, baking powder and instant coffee powder until just combined.

Pour into the prepared pan and bake for 30-35 minutes, or until a toothpick inserted in the center comes out with moist crumbs, but not wet. Do not overbake! Transfer pan to a wire rack to cool completely. They taste best if they have been allowed to sit at least an hour.

Run a knife or offset spatula around the edges of the pan. Pull on the edges of the parchment to lift brownies out of pan. Transfer to a cutting board; cut into 2-inch squares.