Cream together the butter, peanut butter, brown sugar and sweetener until light and fluffy. Add eggs, 1 at a time and beat well after each addition. Blend in milk and vanilla. Thoroughly stir together flour, soda and salt; add to the creamed mixture and beat well. Stir in oatmeal. Drop by teaspoon onto waxed paper on microwave oven glass tray. Cook a dozen at a time on full power for 45 to 60 seconds or until firm, but slightly moist. Allow to cool slightly before removing from waxed paper. Repeat with remaining dough.