Preheat your oven to 350 F, and spray a 9x13" baking dish with non stick cooking spray.
Mix ¼ cup of the butter with all of the brown sugar and pour into the bottom of the casserole dish.
¼ cup Butter, ¾ cup Brown sugar
Scatter the chopped pecans on top of the melted butter and brown sugar mixture, then scatter the cherries in any pattern you like.
½ cup Pecans, ½ cup Cherries
Spoon the crushed pineapple evenly over the chopped pecans and cherries.
1 Pineapple
Sprinkle the pineapple cake mix evenly over the crushed pineapple, smoothing it out so the top is level.
1 Cake mix
Drizzle the remaining melted butter over the top of the dry cake mix, then very last, gently pour the reserved pineapple juice (from the canned crushed pineapple) over the top also.
½ cup butter
Bake in the preheated oven for 35 to 40 minutes, where the edges are browned and pulling away from the casserole dish.
When done, remove from the oven and allow to cool for 10 minutes before serving. Use a spatula to lift out the squares, flipping them onto the plate so the bottom of the cake square is facing up.