1. Heat oven to 350°F.
2. Beat butter, brown sugar and granulated sugar in bowl until creamy. Add eggs and vanilla; beat well. Combine flour, baking soda, salt and cinnamon, if desired; add to butter mixture, beating well. Stir in oats, milk chocolate chips and peanut butter chips (batter will be stiff). Drop by rounded teaspoons onto ungreased cookie sheet.
3. Bake 10 to 12 minutes or until lightly browned. Cool 1 minute; remove from cookie sheet to wire rack. Makes about 48 cookies.
BAR VARIATION: Spread batter into lightly greased 13x9x2-inch baking pan or 15-1/2x10-1/2x1-inch jelly-roll pan. Bake at 350°F. for 20 to 25 minutes or until golden brown. Cool; cut into bars. Makes about 3 dozen bars.