This is the best Chewy Brownie recipe with gooey, chewy inside and crispy outside brownies that have rich chocolate flavor. They're even better than brownies from a box mix!
Preheat the oven to 350F. Line a 9 by 13-inch baking dish with a piece of parchment paper so that it hangs over 2 sides (so you can lift out the brownies later). Spray the inside with cooking spray.
Whisk together the cocoa powder, espresso, and boiling water in a large bowl.
Add the chopped chocolate and whisk until melted. Whisk in the butter and oil, and then cool until lukewarm.
Whisk in the eggs, egg yolks, and vanilla until smooth. Whisk in the sugar.
Stir in the flour, salt, and baking soda until just combined. Stir in the nuts if using.
Pour the batter into the prepared dish and bake until a toothpick inserted inside comes out moist with a couple crumbs, about 30 to 40 minutes. Be careful not to over-bake.
Cool completely before cutting (they will be gooey if they're hot!).
What Type of Cocoa Powder to Use: If you only have Dutch-processed cocoa powder on hand, you can use that instead, but omit the baking soda.
What Type of Oil to Use: I’ve also tried this recipe with vegetable oil and avocado oil (instead of canola oil), and they both work fine.
Storage: Once the brownies are completely cool, wrap them well with plastic wrap. Store them well-wrapped at room temperature for up to 5 days, in the fridge for up to 2 weeks, or in the freezer for up to 6 months.
If You Don't Have Unsweetened Chocolate On Hand: You can substitute with 3 tablespoons of unsweetened cocoa powder + 1 tablespoon of vegetable oil per 1 ounce of unsweetened chocolate.