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Better Box Mix Brownies

How to Make Box Mix Brownies Even Better

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  • Author: Laura Kasavan
  • Prep Time: 5 minutes
  • Cook Time: 25 minutes
  • Total Time: 30 minutes
  • Yield: 12 to 16 brownies
  • Category: Dessert
  • Method: Bake
  • Cuisine: American


Learn how to make box brownies better! These tips elevate your favorite box mix brownies to the next level. You’ll love these fudgy, chewy brownies with crackly tops.


  • 6 Tbsp (84 g) unsalted butter, melted
  • 1 tsp (8 g) instant espresso powder
  • 1 1/2 tsp (6 g) vanilla extract
  • 1 large egg (50 g), at room temperature
  • 1 large egg yolk (17 g), at room temperature
  • 1 18 oz (502 g) box brownie mix
  • 1/2 cup (85 g) semisweet chocolate chips


  • flaky salt (such as Maldon)


  1. Preheat oven to 350°F and line an 8-inch square metal baking pan with parchment paper.
  2. Make brownies: Combine melted butter, instant espresso powder, vanilla, egg, and egg yolk in a large bowl. Whisk until smooth and combined. Add box brownie mix to the bowl and fold in with a spatula just until combined and no flour streaks remain (batter will be thick). Fold in chocolate chips.
  3. Scrape brownie batter into prepared pan. Use a piece of parchment paper to press batter evenly into pan and smooth the top. Gently tap pan once to remove air bubbles.
  4. Bake brownies for 25 to 26 minutes, until the top is set and a toothpick inserted in the center comes out with a few crumbs attached. Remove from oven and place on a wire rack to cool completely. Sprinkle the tops of the brownies with flaky salt.
  5. Lift parchment and place brownies on a cutting board. Cut into squares with a sharp knife. Store leftover brownies in an airtight container at room temperature.


Boxed brownie mix: Use your favorite brownie mix that’s approximately 18 oz (502 grams). For a larger 20 oz brownie mix (567 grams), I recommend increasing the butter to 1/2 cup (112 grams).

Chocolate chips: If the box brownie mix does not include chocolate chips, add up to 1 cup (170 grams) semisweet or dark chocolate chips. If the mix includes chocolate, add at least 1/2 cup (85 g) chocolate chips.

Flaky salt: I use Maldon Sea Salt Flakes.

Peanut butter or Nutella swirl: Measure out 1/3 cup (85 grams) peanut butter or Nutella in a small bowl and microwave for 10 to 15 seconds. Dollop over the top of the brownie batter and gently swirl with a toothpick. Tap pan sharply before baking.

Bake time: May vary based on the size of your brownie mix and any swirls or additions. Start testing for doneness after 25 minutes, and continue to test every 2 minutes until a toothpick emerges with a few moist crumbs attached.