1. Prepare three 8 inch cake pans with parchment paper circles in the bottom and grease the sides. Preheat oven to 350°F (176°C).
2. Combine the flour, pudding mix, baking powder and salt in a medium sized bowl and set aside.
3. Add the butter, brown sugar and vegetable oil to a large mixer bowl and beat together until light in color and fluffy, about 3-4 minutes. Do not skimp on the creaming time.
4. Add the eggs and vanilla extract and mix until completely combined and smooth. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
5. Add half of the dry ingredients to the batter and mix until mostly combined.
6. Add the milk and mix until well combined. The batter will look a little curdled, but that’s ok.
7. Add the remaining dry ingredients and mix until well combined and smooth. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated. Do not over mix the batter.
8. Divide the batter evenly between the cakes pans and bake for 22-25 minutes, or until a toothpick comes out with a few crumbs.
9. Remove the cakes from the oven and allow to cool for about 2-3 minutes, then remove to cooling racks to cool completely.
10. To make the butterscotch frosting, add the butter to a large mixer bowl and beat until smooth.
11. Slowly add the melted butterscotch chips and mix until well combined.
12. Add about half of the powdered sugar, the salt and half of the milk or cream and mix until well combined.
13. Add the remaining powdered sugar and mix until smooth.
14. Add the remaining milk or cream as needed to get the right consistency of frosting. Set frosting aside.
15. To put the cake together, use a large serrated knife to remove the domes from the top of the cakes so that they’re flat, if needed. The cakes should be pretty flat already. Place the first cake on a serving plate or a cardboard cake round.
16. Spread about 1 cup of frosting into an even layer on top of the cake.
17. Add the second layer of cake on top of the frosting.
18. Add another cup of frosting on top of the cake and spread into an even layer.
19. Top the cake with the remaining layer and frost the outside of the cake. Refer to my tutorial for frosting a smooth cake, if needed.
20. Press butterscotch chips into the sides of the cake immediately after frosting it.
21. Use the remaining frosting to pipe shells around the border of the cake.
22. Store cake in an airtight carrier. Cake is best when eaten within 3-4 days.