Gently spoon the batter over the pineapple rings, spreading it out as evenly as you can. Try not to disturb the pineapple too much; it’s fine if a little juice peeks through around the edges.
Cover the slow cooker with the lid. Cook on HIGH for 2 to 2 1/2 hours, or on LOW for 4 to 4 1/2 hours, until the top of the cake is set, the edges are golden-brown, and a toothpick inserted into the cake portion comes out mostly clean.
Once done, turn off the slow cooker and let the cake sit, covered, for 10 to 15 minutes. This rest time helps the juices settle and gives the cake that glossy, slightly caramelized look with a moist, spongy texture.
Serve the cake warm, scooping down through the cake layer to the pineapple rings and syrup underneath. You can serve it straight from the slow cooker for that cozy, rustic feel, or carefully lift out portions with a spatula to keep some of the pineapple rings visible on top.
Variations & Tips
To make this dessert feel a little more classic, you can sprinkle 1/2 to 3/4 cup of brown sugar in the bottom of the slow cooker before adding the pineapple (this technically adds a fourth ingredient, but it gives you a deeper, more caramel-like syrup). If you like a hint of spice, stir 1 teaspoon of ground cinnamon into the dry cake mix before adding the butter. For a slightly lighter version, you can swap half of the melted butter with pineapple juice from a second can of pineapple or use a light cake mix. Want more texture? Add a handful of chopped pecans or walnuts over the pineapple before topping with batter. If you only have pineapple tidbits or chunks, those work too—just spread them in an even layer instead of rings. Leftovers reheat beautifully: store them in the fridge and warm individual portions in the microwave for 20–30 seconds for that just-cooked, cozy-cake vibe on busy weeknights.
