|2||tablespoons unsweetened alkalized cocoa powder|
|1/2||teaspoon baking soda|
|1/4||teaspoon baking powder|
|1/2||teaspoon salt, preferably ultra-fine sea salt|
|1/2||pound (2 sticks) unsalted butter, melted and cooled to tepid|
|1||cup firmly packed light brown sugar, sieved if lumpy|
|1/2||cup granulated sugar|
|3||eggs, lightly beaten|
|3||teaspoons vanilla extract|
|6||packages (1.4 ounces each) milk-chocolate-covered toffee bar candy, chopped into rough chunks|
|1 1/4||cups coarsely chopped walnuts|
|1||cup milk chocolate chips|
2. In a bowl, sift the flour, cocoa, baking soda, baking powder, and salt.
3. In another bowl, whisk the melted butter and light brown and granulated sugars. With a wooden spoon, blend in the eggs and vanilla, mixing until well incorporated. Stir in the flour mixture. Add the toffee, walnuts, and chips.
4. Pour the batter into the baking pan, spreading it into an even layer. Bake for 30 to 34 minutes, or until just set. Transfer the pan to a cooling rack. Let it sit for 30 minutes.
5. Use a sharp knife to cut 4 horizontal rows and 4 vertical rows to make 25 pieces. Cool completely, then recut and use a small offset spatula to remove the bars from the pan. Store in an airtight tin.