2 cans (15 oz. ea) mandarin orange slices, drained
1 (20 oz.) can pineapple slices, drained and cut into quarters
2 cups sweetened shredded coconut
Bring juice from canned pineapple to boil. Whisk together eggs, yolk, and sugar in medium bowl. Add to pineapple juice, whisking continuously over medium heat until it becomes thick (3-4 minutes). Take off heat, stir in butter and salt. Pour in small bowl, cover with plastic wrap and refrigerate for 1 hour.
Bake cake according to package directions. When cooled, slice horizontal into 3 even layers.
Take vanilla frosting, orange juice and orange zest; stir to combine.
Place bottom layer of cake on platter, spread 1/2 of orange frosting on bottom layer, top with mandarin oranges.
Place another layer of cake on top, spread pineapple curd over this layer and top with 4 slices of pineapple rings cut into 1/2.
Add third layer of cake, frost all around the sides with rest of orange frosting. Frost top with cream cheese frosting.
Layer 4 pineapple rings on top, cut into 1/4 and second can of mandarin oranges.
Press toasted coconut into sides and on top of cake.