My grandmother passed down this secret recipe and it is always the star of our June picnics. Only 4 ingredients for the richest dessert you will ever eat.

This slow cooker 4-ingredient gooey butter cake is the kind of rich, over-the-top dessert my grandmother used to make for our June picnics. She swore it was her “secret” recipe because no one believed something this decadent could come from just four pantry staples and a slow cooker. The bottom turns into a dense, buttery cake, while the center stays soft and gooey with a tangy cream cheese richness and a crinkly golden top. It’s simple enough for a busy weeknight but special enough to be the star of any potluck or family gathering.

Serve this gooey butter cake warm, scooped straight from the slow cooker into small bowls or onto dessert plates. It’s plenty rich on its own, but a little vanilla ice cream, lightly sweetened whipped cream, or a handful of fresh berries (strawberries or blueberries are perfect for June) makes it feel extra festive. For picnics, I like to keep it right in the slow cooker on the “warm” setting so everyone can help themselves. A pot of coffee, a pitcher of iced tea, or cold milk for the kids all pair nicely with the buttery sweetness.

Servings: 10-12

1 box (15.25 ounces) yellow cake mix

Prepare the slow cooker: Lightly coat the inside of a 5- to 6-quart slow cooker with nonstick cooking spray or a thin layer of butter. For easier cleanup and lifting, you can also line the bottom and about halfway up the sides with a piece of parchment paper, pressing it into the corners.

Make the cake base: In a medium mixing bowl, pour in the dry yellow cake mix. Add 1/2 cup (1 stick) of the melted butter. Stir with a spatula or wooden spoon until the mixture looks like thick, slightly crumbly dough and no dry mix remains.

Form the bottom layer: Transfer the cake mixture into the prepared slow cooker. Use clean hands or the back of a spoon to press it evenly across the bottom into a firm, level layer. This will be your dense, buttery cake base.

Make the gooey topping: In a large bowl, add the softened cream cheese and beat with a hand mixer on medium speed until smooth and creamy, about 1–2 minutes. Add the remaining 1/2 cup (1 stick) melted butter and mix until fully combined. Gradually beat in the powdered sugar, about 1 cup at a time, on low speed at first so it doesn’t puff everywhere, then increase to medium until the mixture is thick, glossy, and smooth.

Add topping to the slow cooker: Pour the cream cheese mixture over the pressed cake base in the slow cooker. Use a spatula to spread it all the way to the edges in an even layer. It will be thick and will sit on top of the base rather than sinking in.

Cook the gooey butter cake: 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 lightly golden brown and the top looks puffed and slightly crinkly, but the center is still soft and jiggly when you gently shake the slow cooker. Every slow cooker runs a bit differently, so start checking around the 2 1/2-hour mark and avoid lifting the lid too often.

Cool slightly before serving: Turn off the slow cooker and let the cake sit, covered, for 15–20 minutes to set just a bit more. The center should stay gooey and creamy while the edges will be more cake-like and chewy.

Serve: Scoop the warm gooey butter cake straight from the slow cooker with a large spoon or spatula. For cleaner slices, let it cool longer, then lift the parchment and cut into squares. Serve warm or at room temperature.

Store leftovers: Once completely cooled, cover the slow cooker insert tightly or transfer leftovers to an airtight container. Refrigerate for up to 4 days. Rewarm individual portions in the microwave for 15–20 seconds to bring back the gooey texture before serving.

For a slightly less rich version, you can reduce the butter to a total of 3/4 cup, but keep in mind the texture will be a bit less dense and indulgent. If you have picky eaters who aren’t big on tangy cream cheese flavor, you can use 1 1/2 packages of cream cheese instead of 2 and add an extra 1/2 cup of powdered sugar for a milder, sweeter topping (this adds a fifth ingredient if you count carefully, so keep the original version as your true 4-ingredient base). For a little flavor twist that still keeps things simple, use a butter golden or French vanilla cake mix in place of plain yellow, or sprinkle the finished cake with a light dusting of extra powdered sugar just before serving. If your slow cooker runs hot, you can place a clean kitchen towel under the lid (ends flipped up so they don’t touch the heating element) to catch condensation and help keep the top crinkly instead of soggy. Food safety tips: Always soften cream cheese at room temperature for no more than 1–2 hours before using, especially in warm weather, to avoid bacterial growth. Make sure the cake cooks until the edges are set and the center reaches at least 160°F if you’re concerned about doneness; use an instant-read thermometer inserted into the gooey center to check. Once the cake has cooled, refrigerate leftovers promptly within 2 hours, since cream cheese is perishable. Reheat only what you’ll eat and avoid leaving the slow cooker on “warm” for more than 2–3 hours after cooking is complete to keep the dairy safe and the texture at its best.