Preheat oven to 350 F (190 C). Grease doughnut pan and set aside.
In a bowl of stand mixer, combine coconut oil, brown sugar, vanilla extract, and eggs. Using paddle attachment mix until thoroughly combined.
Using a separate bowl, whisk together flour, baking powder, salt, and cinnamon.
Slowly add flour mixture and buttermilk to the stand mixer while on medium speed.
Once batter has reached desired consistency, remove bowl from mixer.
With a spatula fold in whole oats.
Spoon batter into doughnut molds, filling all the way to the edge.
Bake for 15 minutes or until toothpick comes out clean.
Allow doughnuts to cool for 10 minutes before inverting onto cooling rack.
Let cool completely before applying frosting.
Make your frosting!!