Break chocolate into 8 equal pieces. Preheat oven to 375° F In a large bowl, stir together the flour, brown sugar, baking powder, and salt. Cut the butter into 1/2-inch cubes and distribute them over the flour mixture. With a pastry blender or two knives used scissors fashion, cut in the butter until the mixture resembles coarse crumbs. In a small bowl, stir together the peanut butter mixture to the flour mixture and knead until combined. Knead in the peanuts. Pat the dough out into a 1/2-inch thickness on a cutting board. Using a floured 2-1/2 in. to 3-in. diameter crinkled round biscuit cutter, cut out rounds from the dough. Gather the scraps together and repeat until all the dough is used and there are 16 round. Place 8 of the rounds on an ungreased baking sheet. Top each round with a piece of the chocolate and one of the remaining circles of dough. Press the edges gently to seal. Bake for 17-19 minutes, or until lightly browned. Remove the baking sheet to a wire rack and cool 5 minutes. Using a spatula, transfer the scones to the wire rack to cool. Serve warm or cool completely and store in an airtight container.