Preheat oven to 375 (325 for a convection oven).
1. Cream the butter, shortening and sugars.
2. Add eggs and vanilla and beat until well combined.
3. In a separate bowl, stir together flour, salt, baking soda,and baking powder, then add to the butter mixture and combine well.
4. Stir in raisin bran and chocolate chips.
5. Place spoonfuls on an ungreased cookie sheet, approximately 3" apart and bake until edges of cookies turn golden brown, approximately 10 minutes. Let cool a few minutes on the cookie sheet before removing.