Begin by preheating the oven to 325°F. Prepare three 8x2-inch round cake pans by greasing and flouring them. For added security, line the bottom of each pan with parchment paper.

In a microwave-safe bowl, melt the butterscotch chips with two tablespoons of vegetable oil. Microwave in 20-second intervals, stirring between each, until almost melted, then stir to dissolve any remaining bits. Allow it to cool slightly before adding it to the batter.

In a mixing bowl, whisk together the yellow cake mix, flour, and dry butterscotch pudding mix. Add the eggs, sour cream, milk, vegetable oil, vanilla extract, and the melted butterscotch. Blend on low speed until ingredients are just combined, then increase speed to medium for one minute, pausing to scrape down the sides of the bowl. Continue mixing for another minute. The batter may feel thick, but it will bake up light and airy.

Divide the batter evenly across the prepared pans (approximately 6 cups in total). Bake for 22-25 minutes or until a toothpick inserted into the center comes out clean or with just a few moist crumbs. The cake should spring back when gently pressed. Allow the cakes to cool in the pans for 5-10 minutes before turning them out.

Chill a mixing bowl and beaters in the freezer for about 10-15 minutes. Sift the butterscotch pudding mix to remove any lumps or sugar crystals. In the chilled bowl, combine the pudding mix and heavy cream. Using a handheld mixer, blend on low speed initially, then increase to high speed, whipping until the mixture becomes thick and fluffy. If the consistency is too dense, gradually stir in additional heavy cream until the filling reaches your preferred texture.

For the Cream Cheese Frosting

In a mixing bowl, beat the softened butter until smooth. Cut the cream cheese into smaller pieces, then add to the butter, mixing on low to medium speed until fully blended. Pour in the vanilla extract. Gradually add the confectioners’ sugar while beating on low speed to avoid a sugar cloud. Once incorporated, increase speed and mix until the frosting is fluffy but still holds its shape. Be cautious not to overbeat, as the frosting may become too soft. If this happens, refrigerate briefly to firm it up.

Place the first cake layer on your serving plate. Using a piping bag, pipe a ring of cream cheese frosting about half an inch from the edge. Spoon the butterscotch cream filling inside the ring. Repeat this process with the second layer. Place the final cake layer on top.

Fill any gaps between layers with the cream cheese frosting, then apply a thin crumb coat over the entire cake. Chill the cake in the freezer for about 15 minutes to set the crumb coat. Add a second layer of frosting, smoothing it evenly over the cake. For decoration, pipe a border around the top using the remaining butterscotch filling with a large star tip. Press butterscotch chips, or crushed chips if preferred, around the base of the cake for a finishing touch.