A simple box of brownie mix can turn into the richest, fudgiest brownies with just a few easy tweaks. Swap out a few ingredients, stir in some flavorful extras, and you’ll have a batch of unbelievably decadent brownies that taste just like homemade!
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There’s something magical about turning a simple box brownie mix into the ultimate chocolatey treat. With just a few ingredient swaps, you can create a fudgy texture and richer homemade taste. Whether you love crispy edges or gooey centers, these easy upgrades make every batch irresistible.
Adding an extra egg yolk, swapping heavy cream or milk for water, and using melted butter instead of oil deepens the chocolate flavor and smooths the batter. These simple tricks take any boxed brownie mix to bakery-level perfection—once you try them, you’ll never go back!
For more simple and delicious brownies, be sure to check out my recipes for The BEST Homemade Brownies, Frosted Brownies, Best Fudgy Chewy Chocolate Brownie Cookies, Small Batch Brownies, and Homemade Cosmic Brownies!
Why We Love This Recipe
- A few easy upgrades make any box brownie mix taste like rich, fudgy homemade brownies.
- Using melted butter, heavy cream, and an extra egg yolk creates a moist, chewy texture with deep chocolate flavor.
- Fun mix-ins like chocolate chips and flaky sea salt sprinkled on top add extra indulgence to every bite.
What You’ll Need
Scroll down to the recipe card below this post for ingredient quantities and full instructions.
- Box Brownie Mix – The base of this recipe! Any favorite brownie mix works, whether it’s Ghirardelli, Betty Crocker, or another brand.
- Salted Butter – Replaces vegetable oil for a richer flavor and fudgier texture. Unsalted butter works too—just add an extra pinch of salt.
- Large Egg + Egg Yolk – The extra egg yolk adds moisture and chewiness, making the brownies denser and more indulgent.
- Heavy Cream – Enhances the batter’s richness and helps create a smooth, velvety texture. Whole milk or sour cream can work in a pinch.
- Salt – Balances the sweetness and enhances the deep chocolate flavor.
- Pure Vanilla Extract – A simple way to add warmth and depth to the brownies.
- Flaky Sea Salt – Sprinkled on top for a bakery-style finish that elevates the flavor.
- Chopped Chocolate or Chocolate Chips – Melts into the batter for extra gooey pockets of chocolate in every bite.
How to Make Box Brownies Better
- Prep equipment. Preheat the oven to 350°F. Spray a 9×9-inch baking pan with nonstick cooking spray and line it with parchment paper for easy removal.
- Mix batter. In a large mixing bowl, combine the brownie mix, melted butter, egg, egg yolk, heavy cream, salt, and vanilla extract. Stir until everything is well incorporated, but be careful not to overmix—this keeps the brownies fudgy instead of cakey.
- Fill pan. Pour the batter into the prepared pan and spread it out evenly with a spatula. If adding mix-ins like chocolate chips or peanut butter cups, gently fold them into the batter before spreading.
- Bake. Bake for 35-45 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs. The exact baking time depends on the brand of brownie mix and your preferred level of fudginess.
- Cool and finish. Transfer the pan to a wire rack and let the brownies cool to room temperature. While still warm, sprinkle with flaky sea salt for a gourmet touch. Once fully cooled, cut into squares and enjoy!
Recipe FAQ’s
Yes! Swapping water for whole milk or even heavy cream makes the brownies richer and more flavorful.
Adding an extra egg yolk creates a fudgier texture by increasing the fat content, making the brownies chewier and more indulgent.
Use a metal baking pan instead of glass, and line it with aluminum foil. Baking at a slightly lower temperature for a longer time also helps create those crispy edges.
Absolutely! Stir in a teaspoon of instant espresso or instant coffee, add chopped dark chocolate, or use semi-sweet chocolate chips for a deeper chocolate taste.
Keep brownies in an airtight container at room temperature for up to four days, or wrap them tightly in plastic wrap and freeze for up to three months.
Tips for Success
- Use melted butter instead of oil to give the brownies a richer flavor and fudgier texture.
- Stirring in a teaspoon of instant espresso deepens the chocolate flavor without making the brownies taste like coffee.
- Don’t overmix the batter—stir just until combined to keep the brownies dense and chewy.
- For perfect cuts, let the brownies cool completely and use a sharp knife wiped clean between slices.
- A sprinkle of flaky sea salt on top balances the sweetness and gives the brownies a gourmet touch.
What to Serve with Brownies
A scoop of vanilla ice cream melting over a warm brownie takes it to the next level, creating the ultimate dessert combination.
If you love contrast, drizzle caramel sauce or melted peanut butter on top for extra richness.
And if you’re serving them for a special occasion, add a dollop of marshmallow fluff or top with crushed Andes mints for a refreshing touch!
Substitutions and Variations
- Swap melted butter for brown butter to add a nutty, caramelized depth to the brownies.
- Use sour cream instead of heavy cream for an extra tangy richness that enhances the chocolate flavor.
- Stir in chopped candy bars, butterscotch chips, or mini marshmallows for fun mix-ins and added texture.
- For a holiday twist, fold in crushed peppermint patties or sprinkle crushed candy canes on top.
- Drizzle warm caramel sauce over the baked brownies for a gooey, decadent finish.
More Indulgent Brownie Recipes You’ll Adore
- Chocolate Peanut Butter Crunch Brownies
- Pecan Pie Brownies
- Fudgy Oreo Brownies
- Easy Chocolate Turtle Brownies
- Frosted Peppermint Brownies
- German Chocolate Brownies
- Slutty Brownies [Brownie Oreo Chocolate Chip Cookie Bars]
- Irresistible Mississippi Mud Brownies
Doctored Up Box Mix Brownies Recipe
Ingredients
- 1 (16- to 18-ounce) box brownie mix (we like Ghirardelli or Betty Crocker Supreme Original Brownie Mix)
- ½ cup salted butter
- 1 large egg + 1 large egg yolk
- 4 Tablespoons heavy cream room temperature
- ½ teaspoon salt
- 1 teaspoon pure vanilla extract
- Flaky sea salt
- 1 cup chopped chocolate or chocolate chips
Instructions
- Preheat the oven to 350°F. Spray an 9×9-baking pan with nonstick cooking spray and line with parchment paper.
- Add the brownie mix, melted butter, egg, egg yolk, heavy whipping cream, salt, and vanilla to a large mixing bowl. Stir well until everything is evenly combined but be sure not to over-mix your batter.1 (16- to 18-ounce) box brownie mix, ½ cup salted butter, 1 large egg, 4 Tablespoons heavy cream, ½ teaspoon salt, 1 teaspoon pure vanilla extract, 1 cup chopped chocolate
- Pour the batter into the prepared 8×8 pan and spread it out evenly with your spatula.
- Bake the brownies for 35-45 minutes. You should be able to insert a toothpick or knife in the center of your pan and it should come out mostly clean with just a few crumbs when the brownies are done. Do not overbake.
- Remove them from the oven and transfer the pan to a wire rack to cool to room temperature. While the brownies are still warm sprinkle them lightly with flakey sea salt to finish. Cool completely before cutting into squares and serving.Flaky sea salt
Notes
- Be sure to store the brownies in an airtight container and they should last up to 4-5 days. You can also double bag them in a plastic Ziploc type bag and freeze them up to 3 months.
- Brownie mixes vary in weight by brand, but the same amounts of eggs, cream, and butter seem to work with any type of mix.
Storage & Make Ahead
- Store: Keep brownies in an airtight container at room temperature for up to four days to maintain their soft, chewy texture.
- Freeze: Wrap each brownie individually in plastic wrap, then place them in a freezer-safe bag or container for up to three months.
- Reheat: Microwave a brownie for 10-15 seconds to bring back its warm, gooey texture, or let frozen brownies thaw at room temperature.
- Make Ahead: Prepare the batter and store it in the fridge for up to 24 hours before baking, or bake the brownies in advance and freeze them for later.
