This slow cooker 4-ingredient peanut butter cup cake is the kind of rich, chocolatey dessert my grandkids start asking about as soon as the leaves turn. It reminds me of the dump cakes the church ladies used to bring to potlucks back in the 70s—simple pantry ingredients, no fuss, and always the first dish scraped clean. Here, a boxed chocolate cake mix gets dressed up with creamy peanut butter and chopped peanut butter cups, then bakes low and slow until it’s dark, moist, and almost pudding-like around the edges. It’s the sort of recipe you can stir together in a few minutes, walk away from, and come back to a slow cooker full of warm, melty, peanut-butter-swirled cake that truly melts in your mouth.
Serve this cake warm right out of the slow cooker, spooned into bowls so you catch all the soft, gooey edges. A scoop of vanilla ice cream or a dollop of whipped cream melts beautifully over the hot chocolate and peanut butter swirls. A cold glass of milk is a natural match, especially for kids, while grown-ups might enjoy a cup of coffee or hot cocoa alongside. It’s rich enough to stand on its own—no fancy garnishes needed—so it’s perfect after a casual family supper, holiday ham, or a big Sunday pot roast.
Slow Cooker 4-Ingredient Peanut Butter Cup CakeServings: 8-10
Ingredients
1 (15.25-ounce) box chocolate cake mix (any brand, regular or devil’s food)
1 1/4 cups whole milk
3/4 cup creamy peanut butter
2 cups chopped peanut butter cups (about 16 regular-size cups), divided
Directions
Lightly grease the inside of a 5- to 6-quart slow cooker with butter or nonstick cooking spray so the cake doesn’t stick.
In a large mixing bowl, combine the dry chocolate cake mix and the milk. Stir with a wooden spoon or spatula just until the batter is smooth and no dry pockets remain. The batter will be fairly thick.
Scrape the chocolate batter into the prepared slow cooker and spread it into an even layer, smoothing the top as best you can.
Warm the creamy peanut butter slightly so it loosens up: either microwave it in a small bowl for 20–30 seconds or stir it well at room temperature until soft and pourable.
Drizzle the warm peanut butter over the chocolate batter in the slow cooker. Use the tip of a knife or a skewer to gently swirl the peanut butter into the top portion of the batter, creating loose ribbons—don’t fully mix it in.
Sprinkle 1 1/2 cups of the chopped peanut butter cups evenly over the surface of the swirled batter, gently pressing them down just a bit so they sit in the batter but still show on top.
Cover the slow cooker with its lid. Cook on LOW for 2 1/2 to 3 1/2 hours, or until the edges are set and pulling slightly away from the sides and the center is just set but still very moist. The top should look dark, glossy, and a little steamy, and a toothpick inserted near the center should come out with moist crumbs but not raw batter.
Turn off the slow cooker and immediately sprinkle the remaining 1/2 cup chopped peanut butter cups over the hot cake. Cover again and let stand for about 5–10 minutes so the candy softens and gets melty on top.
Serve the cake warm, scooping it straight from the slow cooker with a large spoon. Be careful of the hot crock. If you like, add ice cream or whipped cream on top of each serving. Store any leftovers covered in the refrigerator and reheat gently in the slow cooker on WARM or in the microwave until just warmed through.
Variations & Tips
For a stronger chocolate flavor, use a devil’s food cake mix or one labeled “extra moist” and add a handful of semi-sweet chocolate chips along with the peanut butter cups (this will technically add an ingredient, so think of it as a bonus for special occasions). If you prefer a slightly lighter texture, you can swap the whole milk for 1 cup milk plus 1 large egg, beating them together before stirring into the cake mix. Crunchy peanut butter can be used instead of creamy for a bit of texture in the swirls. To stretch this dessert for a crowd, spoon warm portions into bowls and top with plenty of vanilla ice cream; the ice cream helps balance the richness. If you need to make it ahead, cook the cake earlier in the day, then switch the slow cooker to WARM about 20–30 minutes before serving to gently reheat, adding the final sprinkle of peanut butter cups just before bringing it to the table. For a slightly less sweet version, choose dark chocolate peanut butter cups or use a dark chocolate cake mix. And if you’re serving folks with smaller appetites, cut the peanut butter cups back to 1 1/2 cups total and rely more on the peanut butter swirl for flavor while still keeping that melty, chocolatey look.
