Lightly grease a 9 inch square pan. Sprinkle with peanuts and set aside.
Combine brown sugar and butter in a medium saucepan.
Cook over low heat, stirring constantly, until mixture reaches soft crack stage, about 270 degrees.
Immediately pour over peanuts, spreading to sides of pan.
Sprinkle with chocolate chips, cover with foil, and let stand 2 minutes.
Remove foil and spread chocolate evenly over top.
Chill until firm. Remove cancy from pan and break into pieces.