Preheat oven to 350°F.
In the bowl of a stand mixer or in a large mixing bowl with a hand mixer, cream together the butter, and coconut oil or shortening on low speed until they the sugar starts combining with the fat. Turn the mixer to medium high speed and whip until the mixture is fluffy and the sugar is completely distributed.
Add the egg, molasses and vanilla extract to the butter and beat on medium speed until even.
In a separate bowl, use a whisk to combine the flour, salt, cinnamon, baking soda and powder, and the rolled oats. Add this to the butter mixture along with the buttermilk and beat until thoroughly combined. Stir in the optional goodies.
On a greased or parchment lined cookie sheet, drop generously rounded tablespoons of the cookie dough three inches apart. Form the cookie dough into balls.
Use a flat bottomed drinking glass dipped in sugar to gently flatten the cookie dough.
Bake for 10 minutes, or until the bottoms and edges of the cookies are lightly browned and the cookies are set. Allow cookies to rest on the cookie sheets for one minute before transferring to a cooling rack. Store cooled cookies in an airtight container at room temperature.