Preheat your oven to 325°F. Prepare a 9x13-inch metal baking pan with nonstick cooking spray or parchment paper and set aside.

In a large mixing bowl, combine (1) 15.25-ounce butter cake mix, 3 large eggs, ½ cup melted unsalted butter, (1) 15-ounce can of drained mandarin oranges, and the reserved 2 tablespoons of juice. Use a hand mixer on low speed to mix the batter just until smooth, about 1-2 minutes. Avoid overmixing to prevent the cake from becoming rubbery.

Pour the batter evenly into the prepared pan. Smooth the top with a spatula.

Bake on the center rack for 30–35 minutes. Check for doneness around the 25-minute mark by inserting a cake tester or toothpick into the center; it should come out clean or with just a few crumbs. Tent with foil for the last 5-10 minutes if the top starts to brown too quickly.

Allow the cake to cool completely in the pan on a wire rack before frosting.

To make the frosting, in a medium bowl, combine (1) 3.4-ounce box of instant vanilla pudding and (1) 20-ounce can of crushed pineapple, including the juice. Once combined, add (2) 8-ounce tubs of whipped topping and fold gently until thoroughly combined.

Spread the frosting evenly over the cooled cake. Chill the frosted cake in the refrigerator for at least 1 hour before serving. For best results, allow it to chill for 3-4 hours or overnight, so the frosting sets properly and the flavors can meld. Keep it covered with a lid or plastic wrap while chilling.

If desired, top with slices of more mandarin oranges. Slice into equal squares and ENJOY!