Prepare yellow cake as directed, using a 9 x 13 inch pan. Bake until done, and remove from oven. Poke holes in the top of the cake using a fork.
In a saucepan, combine pineapple with juices and sugar. Cook over medium heat until syrup thickens. Pour over top of warm cake, and cool.
In another bowl, beat milk with pudding. Spread over the pineapple mixture.
Beat whipping cream until soft peaks form, and then beat in confectioners' sugar and vanilla. Spread whipped cream over pudding. Sprinkle toasted coconut over the top of the cake. Refrigerate for several hours or overnight.