Reese’s Cake Mix Cookie Bars (Just 5 Ingredients)
Halloween candy bowls, Thanksgiving potlucks, Friday night bake sales — peanut butter and chocolate is basically the unofficial flavor of fall in every household I know. You grab a bag of Reese’s with the best intentions, and somehow half of it disappears before you even open the oven. But what if the candy IS the recipe — and the whole thing comes together faster than a boxed brownie mix?
These cookie bars use a yellow cake mix as the base, so there’s almost no measuring involved. You get soft, chewy bars loaded with Reese’s Pieces and chopped peanut butter cups in every bite — ready to slice in about 30 minutes flat. Five ingredients, one bowl, zero stress.
Pro Tip
The most common mistake with cake mix bars: treating them like brownies and waiting for a clean toothpick. That’s how you end up with dry, cakey slabs instead of chewy bars. Pull the pan at exactly 22 minutes — the center should still look slightly underdone and the edges will have just turned a pale gold. They firm up as they cool, and that 3-minute window between ‘underdone’ and ‘overbaked’ is where the chew lives. I’ve tested this recipe four times and the 22-minute mark is the sweet spot every single time.
A standard 15.25 oz (432 g) box of yellow cake mix is what you need here — Betty Crocker and Pillsbury both work well. If you can only find a butter cake mix, that’s a fine swap and adds a slightly richer base. Reese’s Pieces and mini peanut butter cups are stocked year-round at most major grocery stores and bulk candy aisles. No Reese’s? Chopped Snickers or M&M’s work as a straight swap.
Reese’s Cake Mix Cookie Bars (Just 5 Ingredients)
12
servings10
minutes22
minutes418
kcal20
minutes52
minutesIngredients
1 box (15.25 oz / 432 g) yellow cake mix
2 large eggs
1/2 cup (115 g) unsalted butter, melted and slightly cooled
1 cup (170 g) Reese’s Pieces
1 cup (150 g) Reese’s Peanut Butter Cups, roughly chopped
Directions
- Preheat your oven to 350°F (175°C). Grease a 9×13 inch (23×33 cm) baking pan and line it with parchment paper, leaving some overhang on the sides. The parchment overhang is your best friend — it lets you lift the whole slab out cleanly for slicing instead of digging bars out of the corners.
- Combine the cake mix, eggs, and melted butter in a large bowl. Mix until a thick, slightly sticky dough forms. The dough will feel denser than a cake batter — that’s right. If your butter was too hot, it can start melting the candy early, so let it cool for 2 minutes before mixing.
- Fold in the Reese’s Pieces and chopped peanut butter cups. You’ll hear the candy pieces clicking against the bowl as you stir — once that sound is even throughout, the mix-ins are distributed well enough.
- Press the dough into the prepared pan in an even layer. Use lightly dampened fingertips to press without the dough sticking to your hands — it spreads more evenly than using a spatula.
- Bake for 20–22 minutes, until the edges are pale gold and the center looks just set. Don’t wait for a fully firm top — the bars will continue cooking on the hot pan for a few minutes after you pull them out.
- Cool in the pan for at least 20 minutes before lifting out and slicing. Slice while slightly warm and the cut edges will have a clean, fudgy look — wait too long and the candy hardens, making clean cuts harder.
Variations
Autumn candy swap: replace the Reese’s Pieces with candy corn and chopped Kit Kats for a classic Halloween candy bowl feel. Chocolate base: use a devil’s food cake mix instead of yellow for a deeper, brownie-like bar that makes the peanut butter flavour pop even harder.
Serving Suggestions
A scoop of vanilla ice cream placed on a still-warm bar turns this into a proper plated dessert. A drizzle of melted peanut butter over the cooled slab adds a visual finish and extra richness. Cold whole milk is the most honest pairing — it cuts through the sweetness without competing with it.
FAQ
Can I make these ahead of time?
Yes — these bars keep well at room temperature in an airtight container for up to 4 days. For longer storage, wrap individual bars and freeze them for up to 3 months; they thaw on the counter in about 20 minutes.
My bars came out dry and crumbly — what went wrong?
Overbaking is almost always the culprit. Cake mix bars have very little margin: two extra minutes can take them from chewy to dry. Pull them the moment the edges turn pale gold, even if the center looks slightly underdone.
Can I use a different size cake mix?
The recipe is calibrated for a 15.25 oz (432 g) box — the standard size you’ll find on most shelves. A smaller box will make the bars denser and harder to spread, while a larger one can make them too thin and prone to overbaking. Makes you wonder what other cake mix sizes could do with a tweaked butter ratio, though.
