Preheat oven to 375 degrees. Line two baking sheets with parchment paper, set aside.
In a large mixing bowl, stir together flour, oats, sugars, baking powder, baking soda and salt. Add slightly beaten egg, softened butter and vanilla. Use a large spoon to work it all together. Add M&M's, chocolate chips and pecans, if using. You may need to use your hands to get everything incorporated.
Roll the cookie dough into 1 1/2 inch balls, place on prepared baking sheet, pressing them down slightly with your hand. Bake for about 10-12 minutes.