12tablespoonsunsalted buttercut into 1-inch pieces
For the coconut-pecan topping:
1cupsweetened shredded coconut
To make the brownies:
Preheat oven to 325 degrees. Line a 13 x 9 inch baking dish with foil and spray lightly with nonstick cooking spray; set aside.
Combine flour, salt, and baking powder in medium bowl; whisk to combine and set aside.
Place the chocolate and the butter in the bowl of a double boiler set over medium heat and stir occasionally until the chocolate and butter are completely melted and combined. Remove bowl from saucepan and gradually whisk in sugar. Add eggs one at a time, whisking after each addition until thoroughly combined. Whisk in vanilla. Add flour mixture in three additions, folding with a rubber spatula until batter is completely smooth and thoroughly combined.
Pour batter into prepared baking dish, smooth the top, and bake for 30 to 35 minutes, or until toothpick inserted into center of brownies comes out with only a few moist crumbs attached. Cool on wire rack to room temperature, about 2 hours.
To make the coconut-pecan topping
Spread pecans evenly on rimmed cookie sheet. Toast in oven until fragrant, 5 to 8 minutes. Allow to cool.
After pecans have finished cooling, whisk egg yolks, sugar and salt in a small saucepan until combined. Whisk in butter, then gradually whisk in heavy cream and vanilla extract. Cook over low heat, stirring constantly, until the mixture is fluffy, begins to thicken, and registers about 180 degrees on an instant-read thermometer, about 10 to 12 minutes. Remove from heat, stir in the pecans and sweetened coconut.
Spread the topping evenly onto the cooled brownies, cover with foil and refrigerated until set, about 2 hours.
Cut into squares and serve.
Storing: Store brownies in an airtight container at room temperature for up to three days.Freezing: Freeze brownies in a single layer on a baking sheet. Once they are frozen, transfer them to an airtight container or bag and store them for up to two months. Let the brownies come to room temperature before serving.Source: barely adapted from Cooks Illustrated, March/April 2004