Preheat oven to 350°F. Grease an 8×8” pan and line with parchment paper leaving 1” hanging over the sides of the pan.

In a medium bowl, whisk together the melted butter, cocoa powder, sugar, brown sugar, and vanilla extract. Whisk in the eggs one at a time until incorporated. Then, stir in the flour, salt, and instant coffee powder until just combined. The batter will be thick.

Pour the batter into the prepared pan and spread evenly. Bake 25-30 minutes, until an inserted toothpick comes out clean. Let cool for 10 minutes.

Place the dark chocolate in a small heat proof bowl. Heat the heavy cream over medium high heat, stirring frequently, just until it starts to boil.

Pour the boiling cream over the chocolate and let sit for 2 minutes. Whisk until smooth, and then add the Irish whiskey, vanilla, and salt. Let sit for 5 minutes and then pour over the baked brownies.

Next, pour the melted white chocolate into a piping bag with a small tip. Pipe stripes in a horizontal pattern across the chocolate. Then, use a toothpick to draw lines vertically across the pan to create a marbled look.

Let cool until completely set, about 1-2 hours. Use the parchment paper wings to remove the brownies from the pan, and slice into 16 bars. Enjoy!