In a mixing bowl, beat butter with an electric mixer on medium to high speed for 30 secs. Add about half the flour, the brown sugar, sugar, egg, baking powder, vanilla, and baking soda. Beat till thoroughly combined. Beat in remaining flour. Stir in oats. Drop by rounded teaspoons 2 in apart onto an ungreased cookie sheet. Bake in a 375° oven for 10 to 12 mins or until edges are golden. Cool cookies on a wire rack. Makes about 48.