Preheat oven to 350°F
Melt the butter and the Santé dark chocolate together. You may microwave below 50% power at 30 second intervals, and mixing between intervals, until smooth. Or you may use a double boiler method at a lower heat
Pour the melted chocolate mixture into a mixing bowl, and whisk in the coconut sugar and malted barley syrup
Whisk in the eggs, vanilla, water and freeze-dried coffee
Sift the dry ingredients into a separate bowl. Once sifted, add this to the mixing bowl and continue mixing. Add the roasted walnuts and mix until well combined
Grease the interior of the 1/8 sheet pan with butter and pour the mixture into the pan
Place in oven and bake for 25-30 minutes, until the toothpick test comes out clean
Remove from oven and let cool before cutting