Mix the flour and sugar in a large bowl and set aside.
Add the oil, butter and water into a saucepan. Turn on medium high and bring to a boil.
Once the mixture starts boiling, pour it over the flour mixture. Use a hand mixer to beat until well blended.
Add the eggs, cinnamon, baking soda and buttermilk. Mix until well blended, scraping the sides of the bowl as needed.
Pour into the prepared pan and bake for 20-30 minutes or until the cake pulls away from the sides of the pan and the center tests done.
Add the butter, milk and 4 cups of powdered sugar into a small bowl. Use a hand mixer to beat until the frosting is creamy and completely mixed. Add more powdered sugar as needed to get to the consistency you’d like.
Spread the frosting on the warm cake.
The calories shown are based on the cake being cut into 20 pieces, with 1 serving being 1 slice of cake. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information.**