Combine the peanut butter and semisweet chips in a double boiler and heat until mixture is smooth. (Alternately, you can melt them in a glass bowl in the microwave). Remove from heat. Add the powdered sugar and peanuts. Stir to mix well. Let sit at room temperature until the mixture is firm enough to shape. Roll into ¾-inch balls and set aside.
Preheat the oven to 400 degrees F.
MAKE THE OUTSIDE COOKIE:
In large bowl, combine the flour, butter, powdered sugar and vanilla; knead until well blended (if the dough is too dry, work in a teaspoon to a tablespoon of milk until it's not so dry.) Shape into one 11-inch log; cut into ¼-inch slices. Lay a slice of dough in your hands and use your fingers to gently spread it out into a thin circle. Place a chocolate-peanut butter ball in the center of the slice. Shape the dough slice around the filling, seal and roll into a ball with your hands. Roll the ball in the powdered sugar (add colored sanding sugar if you're making a holiday cookie), and place on un-greased cookie sheet.
Bake for 10 minutes. Cool slightly. Roll in the powdered sugar mixture again while still warm.