Ingredients
- 1 (15 oz) box Duncan Hines Dark Chocolate Fudge Cake Mix, unprepared
- 1 (3.4 oz) box Jell‑O Instant Chocolate Pudding, unprepared
- 4 large eggs
- 1 cup sour cream
- ¾ cup vegetable oil
- ½ cup whole milk
- 1 tablespoon vanilla extract
- ¼ teaspoon salt
- 1 bag mini Reese’s Pieces
- 1 batch peanut butter frosting (your “Best Peanut Butter Frosting”)
- 24 Reese’s Miniatures
Ingredients and Why They Matter
- Dark Chocolate Fudge cake mix (15 oz): Provides the base structure and chocolate flavor; Duncan Hines dark chocolate fudge is popular in doctored cake recipes because it bakes up moist and fudgy and takes extra add‑ins well.
- Instant chocolate pudding mix (3.4 oz): Adds cocoa depth and extra starch, which boosts moisture retention and gives the cupcakes their dense, bakery‑style crumb.
- Eggs (4 large): More than the box calls for, they add structure and richness so the cupcakes can be cored and filled without collapsing.
- Sour cream (1 cup): The key to ultra‑moist cupcakes; the fat and acidity tenderize the crumb and keep them soft for days.
- Vegetable oil (¾ cup): Oil stays liquid at room temperature, which is why these cupcakes stay moist even after chilling; it also helps them feel fudgy rather than spongy.
- Whole milk (½ cup): Thins the thick sour‑cream batter to scoopable consistency while adding just enough extra fat for richness.
- Vanilla extract (1 tablespoon): Amplifies both the chocolate and peanut butter notes and balances the box‑mix flavor.
- Salt (¼ teaspoon): Rounds out sweetness and keeps the chocolate from tasting flat, especially important with candy filling and sweet frosting.
- Mini Reese’s Pieces: Provide the crunchy, colorful peanut butter candy center that surprises when you bite into the cupcake.
- Peanut butter frosting: A creamy, fluffy topping that delivers the main peanut butter hit; using a butter‑based, not glaze‑style, frosting gives stability for piping tall swirls.
- Reese’s Miniatures (24): A final garnish that visually signals the flavor and adds one more chocolate‑peanut butter element.
Step‑by‑Step Instructions
I preheat the oven to 375°F and line a standard 12‑cup muffin pan (or two pans) with 24 cupcake liners, making sure the liners sit flat for even domes. In a large mixing bowl, I combine the dark chocolate fudge cake mix, instant chocolate pudding mix, eggs, sour cream, vegetable oil, whole milk, vanilla, and salt. Using a hand mixer or stand mixer, I beat the mixture on medium speed for about 2 minutes until completely smooth, thick, and glossy, scraping down the sides of the bowl as needed.
Once the batter is smooth, I fill each cupcake liner about ¾ full—this thick batter holds its shape and gives nicely domed tops. As soon as the pans go into the oven, I immediately reduce the temperature from 375°F to 350°F; the initial higher heat helps set the cupcake edges quickly for a higher rise, while the lower temperature finishes baking the centers without drying them out.
I bake the cupcakes for 18–20 minutes at 350°F, or until the tops spring back lightly when touched and a toothpick inserted near the center comes out with a few moist crumbs but no wet batter. Then I remove the pans from the oven and let the cupcakes cool in the pans for about 5–10 minutes before transferring them to a wire rack to cool completely; filling or frosting while warm can cause the candy center to melt too much and the frosting to slide.
Once the cupcakes are completely cool, I use a cupcake corer or a small paring knife to cut a plug out of the center of each cupcake, stopping about two‑thirds of the way down so I don’t cut through the bottom. I drop several mini Reese’s Pieces into each cavity (you can fill it fully, or leave a little space at the top), gently pressing them in so they sit snugly without cracking the cupcake.
Meanwhile, I prepare a batch of peanut butter frosting—usually a standard combination of butter, creamy peanut butter, powdered sugar, vanilla, and a splash of cream—whipped until thick, smooth, and pipeable. I transfer the frosting to a piping bag fitted with a large star or round tip and pipe tall swirls over each filled cupcake, completely covering the filled center. Finally, I press one Reese’s Miniature into the top of each frosted cupcake so it sits upright or at a slight angle.