14 ounces (60% cacao) bittersweet chocolate bar, coarsely chopped
1 1/2 cups unsalted butter
2/3 cup unsweetened cocoa
6 tablespoons canola oil
2 tablespoons vanilla extract
2 1/3 cups granulated sugar
1 cup packed light brown sugar
6 large eggs
1 cup all-purpose flour
2 tablespoons cornstarch
1 1/2 teaspoons kosher salt
1/2 teaspoon baking powder
7 ounces (56% cacao) semisweet chocolate bar, coarsely chopped
3/4 cup heavy cream
1 tablespoon unsalted butter
1/8 teaspoon kosher salt
1/4 cup rainbow candy-coat
Directions
Prepare the Brownies: Preheat the oven to 350 degrees F (175 degrees C). Line a 13- x 9-inch baking pan with aluminum foil, leaving a 2-inch overhang on short sides. Coat foil and sides of pan with baking spray; set aside.
Microwave chocolate and butter in a large microwavable bowl on HIGH, stirring in 30 second intervals, until fully melted and smooth, about 2 minutes total. Whisk in cocoa, canola oil, and vanilla until fully combined.
Whisk sugar and brown sugar into chocolate mixture until combined. Add eggs, 1 at a time, whisking until smooth and combined after each addition, about 2 minutes total. Gently fold in flour, cornstarch, salt, and baking powder until just combined, making sure not to overmix the batter, about 45 seconds.