Slow Cooker Peanut Butter Cup Cake

Serves: 6 | Prep Time: 10 min | Cook Time: 3 hours

Ingredients

Cake Ingredients

• 1 package Better Batter Yellow Cake
• 1 c water
• 3 eggs
• 1/2 c creamy peanut butter
• 1/3 c unsalted butter, at room temperature
• 1/2 c chocolate syrup, such as Hershey's

 

Glaze Ingredients

• 3 Tbl creamy peanut butter
• 2-3 Tbl milk
• 3/4 c powdered sugar
• 2 Tbl chocolate syrup
• 10-20 mini-sized chocolate covered peanut butter cups, such as Reese's, chopped

 

You will also need:

• cooking spray
• 5 - to 6- quart slow cooker

Instructions

Special Note: I did not try this recipe yet with a slow cooker disposable liner. That may make it easier to remove the baked cake when it is ready though, as compared to using two spatulas to lift it up and out of the bowl before serving.

 

Prepare the slow cooker. Spray a 5- to 6-quart slow cooker with nonstick cooking spray. Set aside.

 

Make the cake batter. In a large bowl using a handheld mixer, beat the cake mix, eggs, butter, water, and 1/2 c peanut butter on low speed for 30 seconds. Increase to medium speed for 2 minutes, scraping the bowl to incorporate all the ingredients. The batter will be slightly thick.

 

Make the chocolate fudge batter. Remove 2/3 c of the cake batter and place it in a smaller mixing bowl. Stir in 1/2 c chocolate syrup and mix well to combine.

 

Layer in the cake batters. Spoon half of the yellow cake batter into the slow cooker followed by all of the chocolate fudge batter. Add remaining yellow cake batter and with a knife or the handle of a spatula, swirl the batters together. Cover; cook on high for 1 hour, reduce heat to low and cook for up to 2 more hours or until a toothpick inserted in the center of the cake comes out clean. Watch to make sure the sides of your cake do not burn if you have a slow cooker that cooks unevenly.

 

Cool the cake. Once the cake is done, remove the lid and turn off the slow cooker. Remove the ceramic base from the cooker and set it on a wire rack to cool, about 15 minutes.

 

Make the peanut butter glaze. While the cake is cooling, make this over-the-top peanut butter glaze. In a small mixing bowl, whisk together 3 Tbl peanut butter with 2 Tbl milk until smooth. Add in powdered sugar 1/4 c at a time, whisking until smooth. If the glaze is too thick, add in 1 Tbl additional milk until you reach your desired consistency.

 

Serve warm. Carefully lift the cake out of the slow cooker bowl and slice or use a large spoon to scoop the cake onto plates. Drizzle with the peanut butter glaze, top with a small drizzle of chocolate syrup, and sprinkle on some chopped peanut butter cups.

 

Adapted from Moms with Crockpots, by Jennifer Lathom. Updated in 2025. Original photo by Jennifer Lathom