Preheat the oven to 350° F (176° C). (It will take longer for your oven to heat up than it will to assemble the dump cake so be sure to do this first.)
Dump 2 cans of pineapple into a large ceramic baking dish. Spread it out evenly on the bottom.
Sprinkle the contents of a box of vegan cake mix evenly on top of the pineapple. Use the back of a fork to spread it out evenly making the cake mix power as flat as possible.
Pour 3/4 cup of melted butter evenly over the top of the cake mix.
Place in a 350° F (176° C) oven for 50-55 minutes until golden brown.
Allow cooling for about 15 minutes before serving. (It's great with a scoop of vegan ice cream on top.)
Notes
Be sure to spread each layer out very evenly. This will allow the cake mix to soak up the liquid from the pineapple and get crispy and golden brown on top because of the melted butter.
Watch the cake towards the end of cooking so it doesn't burn. It will turn golden brown quickly after about 50 minutes of cooking.