Preheat your oven to 350°F (175°C). Grease a 9x13 inch baking pan or line it with parchment paper for easy removal.
In a double boiler or microwave-safe bowl, combine the coarsely chopped unsweetened chocolate and cubed unsalted butter. Heat gently until melted and smooth, stirring occasionally. Remove from heat and let cool slightly.
In a large mixing bowl, combine the melted chocolate mixture with 1 cup of sugar. Whisk until well combined. Add the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in 1 teaspoon of pure vanilla extract.
In a separate bowl, whisk together 1/2 teaspoon of salt, 1 cup of all-purpose flour, and 1/2 cup of malted milk powder. Gradually add the dry ingredients to the chocolate mixture, folding gently until just combined.
Chop the Whoppers into smaller pieces, then fold them into the brownie batter. This will ensure you get that delightful malted crunch in every bite.
Pour the brownie batter into the prepared baking pan. Bake for 25-30 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Avoid overbaking to keep them chewy.
While the brownies are cooling, prepare the ganache. In a small saucepan, heat 1/2 cup of heavy cream until it begins to simmer. Pour it over the 4 ounces of chopped semisweet chocolate in a bowl. Let it sit for a minute, then stir until smooth and glossy.
Once the brownies are completely cool, pour the ganache over the top, spreading it evenly. Allow the ganache to set before slicing the brownies into squares.
