Preheat oven to 375 degrees F (190 degrees C). Grease baking sheets, or line with parchment paper. In a large bowl, cream together the butter and sweetener until smooth. Beat in the eggs one at a time, then stir in the rum extract. Combine the almond flour, baking powder, and espresso powder; stir into the creamed mixture until well blended. The dough will be stiff, so mix in the last bit by hand. Mix in the chocolate pieces and nuts. Divide dough into two equal parts. Shape into 9x2x1 inch loaves. Place onto the baking sheet 4 inches apart. Brush with a mixture of water and yolk.
1/3 cup butter, 1/2 cup Natural Sweetener, 1/2 teaspoon stevia glycerite, 2 large eggs, 1 teaspoon rum extract, 2 cups blanched almond flour, 2 teaspoons baking powder, 2 tablespoons instant espresso powder, 1 bar The Good Chocolate, 1/2 cup walnuts