Preheat oven to 375 °F (≈190 °C). Prepare two 8‐inch cake pans with nonstick spray. Presift cake flour four times, then whisk with baking powder, baking soda and salt. :contentReference[oaicite:1]{index=1}

Using an electric mixer, beat butter until creamy. Add sugar and beat for about 2 minutes until light. Mix in pudding mix, then add eggs one at a time, and vanilla extract. :contentReference[oaicite:2]{index=2}

Alternate adding dry flour mixture and buttermilk to batter until fully incorporated. Then fill prepared pans and bake for about 18-22 minutes or until tops are golden and spring back. :contentReference[oaicite:3]{index=3}

Allow cakes to cool in pan 5–10 minutes, then transfer to a wire rack or freezer to cool further for easier frosting. :contentReference[oaicite:4]{index=4}

In a saucepan, bring water + half-and-half to a boil. Stir in corn starch and sugar. Cook until thickened (2-3 minutes). Remove from heat and stir in butter and vanilla extract. Cool—the vanilla cream sauce is ready. :contentReference[oaicite:5]{index=5}

For the butterscotch cream filling: beat cream cheese until smooth, mix in instant butterscotch pudding, then fold in thawed whipped topping. :contentReference[oaicite:6]{index=6}

For the vanilla buttercream frosting: beat butter and shortening until smooth and creamy; add vanilla extract and gradually beat in powdered sugar until light and fluffy. :contentReference[oaicite:7]{index=7}

To assemble: Remove cake domes if necessary. Place bottom layer on cake board, drizzle butterscotch sauce, spread butterscotch cream filling leaving ⅓ inch edge bare. Top with second layer. Crumb-coat with vanilla buttercream and chill 15-20 minutes. Apply final frosting. Drizzle butterscotch sauce over top and zigzag vanilla sauce. Garnish as desired. :contentReference[oaicite:8]{index=8}