• For the Butterscotch Layers
• Preheat the oven to 325 degrees,  Grease and flour three (8x2 inch) round cake pans. We like to also put a circle of parchment (or waxed paper) into the bottom of each pan to ensure that nothing sticks.
• In a microwave safe bowl, combine the ¾ cup butterscotch chips with 2 tablespoons vegetable oil and microwave in 20 second increments or less, stirring in between until almost completely melted. Then stir until the remaining bits of butterscotch have disappeared. It shouldn't be very hot when adding to cake batter.
• In a mixing bowl, combine the dry ingredients: yellow cake mix, flour, and butterscotch pudding mix.  Whisk to blend.  Add the eggs, sour cream, milk, vegetable oil, vanilla extract, and melted butterscotch. 
• Mix on low speed to blend increasing to medium speed for 1 minute.  Scrape the sides and bottom of the bowl and mix another minute.  The melted butterscotch gives the batter a somewhat heavy consistency but don't worry- cake will be light and fluffy.
• Divide the batter among the three prepared pans.  (Makes approximately 6 cups of batter). It doesn't look like much in the pan but they bake up nice and fluffy.
• Bake at 325 degrees for 22-25 minutes or until a toothpick inserted into the center comes out clean or with just a few crumbs attached. It should also spring back when lightly pressed with your finger.
• Allow to cool for 5-10 minutes before turning out.

For the Butterscotch Cream Filling

• We prefer to sift the pudding mix first as sometimes there are sugar crystals that don't fully dissolve. Chill a mixing bowl and beaters in the freezer for about 10-15 minutes. Combine the pudding mix and heavy cream the chilled bowl. I prefer to mix with a hand held mixer, but a whisk is just fine too.
• If using a hand mixer, start on low speed until well combined. Then, switch to high speed and whip the pudding until thick and fluffy.
• If butterscotch mousse/cream is too thick, mix in small amounts of heavy cream to reach desired consistency.

For the Cream Cheese Frosting

• Cut the butter into slices and add to the bowl of your mixer. Beat on low to medium speed until the butter is softened and smooth.
• Cut the cold cream cheese into pieces and add to the butter, beating at low to medium speed until incorporated. If you are using a hand mixer you may need to soften the cream cheese a bit more.
• Add the vanilla. Gradually add the powdered sugar beating on low speed until blended. Cover the bowl with a towel to keep down the cloud of powdered sugar.
• Increase mixing speed and beat until fluffy. Don't over beat or it will become too soft. If it becomes too soft, just refrigerate a short while to firm it up a bit.
• This frosting will pipe best if used while still chilled. You can make it in advance, refrigerate and when ready to use let it soften slightly (do not microwave) and remix.

Cake Assembly

• Place the first cooled cake layer on your cake plate or pedestal. I like to pipe a dam with my cream cheese frosting about ½ inch from the edge of the cake, using a disposable piping bag with the tip snipped away. Then, spread the butterscotch cream filling within the dam.
• Place second cake layer on top and repeat the above steps. Top with third cake layer.
• Fill in any remaining gaps between the cake layers with the cream cheese frosting and then crumb coat. I like to chill the cake at this point in the freezer for about 15 minutes to firm things up. (Refrigerate the bowl or piping bag of cream cheese frosting as needed to firm things up as well).
• Frost the second coat of frosting. We used a cake come to add decoration. I piped a top border using the remaining butterscotch cream filling using a 1M large star piping tip.
• Press butterscotch chips (or crushed butterscotch chips if you prefer) around the base of the cake.