If the cake layers do not bake evenly, you can use a bread knife to trim the top off and make it flat which is easier for decorating. If you froze the cake layers, you will need to let the cake layers thaw just a bit before trimming.
Start with the frozen/semi-thawed cake layers, and place one layer on a cake board. You can use a spoonful of buttercream as “glue” between the cake layer and cake board if you like.
I recommend stacking & trimming your cake layers into a pineapple shape BEFORE filling with buttercream and curd. You’ll see in the photo I did not do that and it was a bit of a mess! To make a pineapple shape, stack all 3 cake layers without buttercream or filling; then simply use a serrated knife to trim around the outsides, taking the most off the top cake layer; less off the middle cake layer; and even less off the bottom layer. It doesn’t have to be perfect; the piped buttercream will cover any mistakes.
Unstack your top 2 plain cake layers. Starting with the bottom cake layer (already “glued” to the cake board with buttercream), pipe a circle of buttercream around the perimeter of the cake layer to create a barrier; add a thin layer of buttercream then spread a generous amount of pineapple curd over that.
Add your second cake layer and repeat with the buttercream/pineapple curd, top with 3rd cake layer; then frost the outside with the buttercream using an offset spatula.
Using a Wilton 1M tip, fill your piping bag with buttercream and pipe small stars all around the cake, starting with the bottom, working your way around to the top.
Using a sharp knife, cut a slit in the top the cake for each of your pineapple leaf pieces. I created two separate pieces so I cut two slits parallel to each other. Carefully place leaf pieces into slits, arranging the larger piece in the back.
Top with Sweetapolita “Soft Serve” sprinkles.