Preheat oven to 325°F and grease a 13x9 baking pan well.
In a small saucepan melt together then 4 squares of unsweetened chocolate and the 1 cup of butter. Stir occasionally.
Allow the butter and chocolate to melt completely and set aside.
In a large bowl, beat the room temp eggs, sugar, and vanilla, until well blended.
Pour the melted chocolate mixture into the bowl and mix well.
Add the cocoa powder, salt, baking powder, and flour into the bowl and blend well.
Pour the brownie mix into the prepared pan and spread evenly.
Bake for about 25 to 30 minutes. Remove and set on a wire rack to cool. Start preparing frosting.
Chocolate Frosting
In a small saucepan, melt together the 2 unsweetened chocolate squares and the ½ cup of butter. Stir until melted.
In a bowl, add in the 4 cups of confectioner's sugar and vanilla.
Pour the melted chocolate mixture into the confectioner's sugar and beat with a hand mixer.
Add in the half and half and beat until creamy. Add more half and half 1 tablespoon at a time if needed.
Spread the frosting over the brownies while still warm and spread evenly.
Allow brownies to cool on a rack for 3 hours before cutting and serving.
Notes
TIP: You can also place the brownies in the refrigerator and allow them to cool this way. Allow at least 30 minutes on the counter with frosting to allow the brownies and frosting to set.