Preheat oven to 165 degrees C/ 325 degrees F. Line the baking tin with baking parchment such that it overlaps the sides. Repeat with the other sheet in the opposite direction thus lining the pan completely. Spray/brush oil along the surface. Sift the flour and baking powder 1-2 times & keep aside.
Met the butter and chocolate in a double boiler or in a heavy bottomed saucepan on a slow heat until the chocolate is melted. Remove and whisk well to avoid any lumps.
Whisk in the sugar and one egg at a time. Stir in the vanilla, salt and food colour. Add the sifted flour and fold. Pour the batter into the prepared tin and bake for 30-35 mins till the surface is puffed and dry and the skewer inserted comes out a bit moist. Remove the cake tin and cool completely on a wire rack
Preparing the frosting
Beat the cream cheese and butter until light and fluffy. Add the vanilla and mix. Add the sifted powdered sugar and blend well.
Lift the brownies out of the pan with the help of the foil. Place on a cutting board and peel away the foil from the sides. Spread the frosting evenly using a spatula. Decorate with sprinkles if desired. Cut into bites of 1-1/4"x1-1/4" or into 16 pieces for larger brownies. Wipe the knife after each slice to achieve clean cuts
For the brownies, I used a blend of salted & unsalted butter and so I skipped the salt. Do note that these brownies are supposed to taste a bit tart and salty, so you may want to increase the sugar slightly. I used regular granulated sugar that I powdered in a dry grinder.
After the brownie has cooled completely, slather it with the frosting only when you are ready to serve as it may dribble down the sides (as you see in my pictures). Alternatively you can prepare the frosting and refrigerate the cake until you are ready to serve. However, brownies taste best at room temperature.
Always use a new/fresh package of cream cheese to avoid a sour taste to the frosting. If it is a bit sour you can add a little extra sugar to it