Cake Layers: Preheat your oven to 350°F (175°C). Prepare three 8-inch cake pans by greasing them generously with vegetable shortening, dusting with flour, and setting aside.

In a medium-sized bowl, whisk together the flour, instant pudding mix, baking powder, and salt. Set aside.

In the bowl of a stand mixer fitted with a paddle attachment, cream together the butter, brown sugar, and granulated sugar until light and fluffy.

Add the vegetable oil, vanilla extract, and rum extract, mixing until just combined.

Add the eggs one at a time, mixing well after each addition.

Add half of the dry ingredient mixture and mix until no dry spots remain.

Slowly pour in the milk and mix until fully incorporated.

Add the remaining dry ingredients and mix until no dry spots remain. Scrape the sides and bottom of the bowl to ensure all ingredients are well combined.

Divide the batter evenly among the three prepared pans and gently tap the pans on the counter to release any air bubbles.

Bake for 22-25 minutes or until a toothpick inserted in the center comes out clean.

Remove from the oven and allow the cakes to cool in the pans for 10 minutes. Then invert them onto a wire rack to cool completely.

Frosting: In the bowl of a stand mixer fitted with a paddle attachment, cream the butter until light and fluffy.

Add the melted butterscotch chips and mix on medium-high speed until well combined.

Add half of the powdered sugar and mix until there are no dry spots remaining. Scrape the sides and bottom of the bowl.

Add the remaining powdered sugar and mix until just combined. Increase the speed to high and mix for 2-3 minutes until fluffy.

Add the heavy whipping cream and mix until just incorporated. Increase the speed to high and mix for 3-4 minutes until the frosting is light and fluffy. If needed, add more heavy cream, one tablespoon at a time, until you achieve a spreadable consistency.

Assembly: If necessary, use a large serrated knife to remove the domes from the top of the cakes.

Place the first cake layer, face down, on a cake plate or stand. Spread about ¾ cup of frosting evenly over the top.

Repeat with the remaining layers of cake.

Once the final layer is placed, cover the entire outside of the cake with a thin layer of frosting. Refrigerate for 10-15 minutes.

Cover the cake with the remaining frosting and smooth it out. If desired, reserve about ¾ cup of frosting to pipe around the top edge of the cake. Refrigerate the cake while you prepare the drip.

Butterscotch Drip: Place the butterscotch chips and heavy cream in a microwave-safe bowl. Microwave in 30-second intervals, stirring in between, until melted and smooth.

Remove the cake from the refrigerator and immediately apply the butterscotch ganache to the top of the cake, allowing some to drip down the sides. For better control, use a spoon to apply the drip.

Refrigerate until ready to serve.