In bowl of electric mixer, cream butter or margarine, peanut butter, molasses, sugar and maltose.
Add egg; beat well. Stir together flour, baking soda, and cream of tartar; stir into creamed mixture. Mix well. Cover and chill 1 hour.
Use 1 level tablespoon of dough for each cookie and roll into ball.
Place on greased baking sheet.
Flatten lightly with floured fork.
Bake in a preheated 350° oven for 10 to 12 minutes.
Let cool 1 minute.
Remove from baking sheet and cool on wire racks.