Recipe

You’ll need two tools to build this cake: an 8 inch x 26 inch piece of clear acetate (available at craft or paper supply stores) and a bent spoon to let you to spread the filling inside the acetate ring. If you can’t find acetate that’s 26 inches long, tape pieces together. For the spoon, bend an old one at the base of its neck.

Prep Pan

1. Preheat oven to 350°F.
2. Spray 13 inch x 17 1⁄2 inch baking sheet with cooking spray and line bottom with parchment.

Make Batter

1. Stir flour with baking powder and salt in bowl. Set aside.
2. Beat butter with sugar using electric mixer until fluffy and pale in color.
3. Beat in oil. Beat in eggs, one at a time, making sure each egg is incorporated before adding the next. Scrape down bowl as needed.
4. Stir sour cream into milk.
5. Add flour to butter mixture in three additions, alternating with milk mixture, starting and finishing with flour. Blend until combined.
6. Pour out onto baking sheet and spread evenly across pan.

Bake and Cool Cake

1. Bake 30 minutes or until cake tester inserted into center of cake comes out clean and edges of cake begin to pull away from sides of pan.
2. Remove pan from oven and transfer to rack.
3. Run sharp knife along edges of pan to release sides of cake. Let cool fully in pan.
4. Once cool, leave cake in baking sheet, cover with foil or plastic wrap and transfer to fridge. Chill until cold, at least 2 hours or overnight.

Make Frosting

1. Beat cream cheese with butter using electric mixer until light and fluffy.
2. Gradually beat in icing sugar until combined. Beat in vanilla. Cover and reserve.

Cut Cake Rounds

1. Carefully flip cake out of baking sheet onto countertop lined with parchment paper. Peel parchment off cake bottom and discard.
2. Shift cake so short ends point north and south on counter. Take 8 inch-round baking pan and trace 2 circles, using knife, in northwest and southeast corners of cake. Trace 2 semicircles on northeast and southwest corners. Cut out traced portions, reserving extra cake separately.
3. On freezer-safe plate or tray, fit together 2 semicircles to form 1 8 inch-diameter circle; trim as needed to make 8 inch-diameter circle (this will be bottom layer of cake).

Assemble Cake

1. Placing acetate on its edge, wrap perimeter of bottom layer of cake, fitting snuggly and tape acetate together to keep in place (this will stabilize cake as you build it). If you have any gaps between acetate and cake, crumble up reserved leftover cake and pack into gaps (this will not show later).
2. Drop 1⁄4 cup raspberry jam onto cake layer and spread right up to acetate using bent spoon.
3. Drop 1 cup frosting onto jam and spread to edges.
4. Slip second layer of cake into acetate mold. Add more reserved cake crumbs as needed to fill in any gaps.
5. Repeat with jam, then frosting.
6. Slip in third cake layer, adding crumbs as needed, and repeat with jam and frosting. Freeze cake overnight. Top with sprinkles.