Brownies: Preheat oven to 350°F. Spray a 13x9-inch baking pan or baking dish with cooking spray. Set aside.
In medium saucepan, melt chocolate and butter over medium-low heat, stirring constantly until completely smooth.
Remove saucepan from heat. Add flour, sugar, vanilla, baking powder, salt and eggs mixing until fully combined. Spread brownie batter evenly into prepared pan.
Bake 30 minutes or just until center is set and a toothpick inserted into the center shows moist crumbs. Cool completely, on a cooling rack about 1-2 hours.
Coconut Pecan Frosting: Spread pecans in a single layer on a baking sheet. Toast in a 350°F oven for 6-8 minutes until lightly golden. Set aside to cool.
In a heavy bottomed saucepan over medium-high heat, melt butter with milk, granulated and brown sugar, corn syrup and salt.
Cook while stirring until the sugar has dissolved, then lower the heat to medium. Whisk 1/4 cup of the warm liquid into egg yolks to temper, then whisk the egg yolks into the saucepan.
Cook over medium stirring until thickened around 12-15 minutes. The consistency should coat the back of a spoon like a thin pudding. [Tip: The icing will thicken more as it cools.]
Remove from the heat and add the vanilla extract, toasted pecan pieces and coconut flakes. Pour into a bowl and cool to room temperature while brownies cool.
Frost the top of the brownies. Store in an airtight container chilled.
Bring to room temperature, cut into squares for serving.