In a medium-mixing bowl, add the oatmeal and sift in the flour, baking powder, baking soda, and salt. Stir together.

In a electric mixing bowl, beat at medium speed the peanut butter and butter until smooth. 

Add in the sugar and continue beating until well blended. 

Next, add in the eggs and vanilla. 

Finally, pour in the oatmeal mixture and continue until well beaten. 

Wrap in plastic wrap and chill in refrigerator for 2 hours.

Take dough and roll into 1-inch balls. 

Place on ungreased cookie sheet about 2 –inches apart. 

Flatten cookie ball with floured-fork, making criss-cross pattern. 

Put into oven and bake for 8 to 10 minutes or until lightly browned. 

Cool on wire rack.