Chop the milk chocolate into small pieces. In Indian climatic conditions, milk chocolate melts fast. So keep it in the freezer while preparing the rest.
In a saucepan or a heavy bottomed pan, melt the butter (chopped into small cubes, then it melts faster).
Add the sugar and cocoa. Stir it and then add the flour with the baking soda. Give it one mix and then take the pan off the heat.
Beat the 4 eggs with the vanilla and add it to the batter.
There is no need to work hard behind making a smooth batter. It can be all cluggy and still alright. Just make sure that the eggs have been incorporated thoroughly.
After this, taken the chopped milk chocolate nuggets out of the freezer and add to the batter. give it a gentle swirl. The reason I put the chocolates in the freezer is this. The batter is anyway a little warm which might completely melt the chocolate in case not frozen. This way they retain some of their shape.
Grease and flour a brownie tin (11.5 x 9.5 inches or similar or closer size). You can even stick butter paper to the bottom using little batter.
Pour the batter in the pan and using a spatula, gently spread the batter to all corners evenly.
Place it in the middle rack of a preheated oven at 180 degrees c and bake for 20 to 25 mins. When you place a skewer inside to check whether the brownie is done or not, a little bit can stick to the skewer. That is the consistency you would want.
Take it out and let it cool down before taking it out of the tray or the brownie may break. Once cooled down, dust icing sugar (completely optional) and then cut into euqal squares.
Serve immediately or store in an air tight container.