In a food processor, combine flour, baking powder, 3/4 cup of the sugar and ground peppercorns. Whirl until blended.
In a small saucepan, stir butter over medium heat until browned, stirring through the white foam to check. Add to the flour mixture and whirl until the dough forms a ball. If after a minute or so, it's still not in a ball, just put it in plastic wrap and squeeze together until it forms a ball.
Pinch off 1-inch pieces of dough and roll into a ball. Arrange balls, slightly apart, on a cookie sheet lined with parchment paper. Dip the bottom of a small glass in the remaining sugar and press each ball gently to about 1/2 inch thickness. Press a peppercorn into the center of each cookie. Sprinkle with additional sugar, if desired.
Bake on the lowest rack of a 300 degree oven until browned on the bottom, about 20-25 minutes. Transfer the cookies to a rack and let cool completely. Store at room temperature or freeze. They're delicious right out of the freezer!