Put 1 tablespoon of all-purpose flour and ½ cup of water in a deep bowl. Mix it well till no lumps. Now Cook on low flame by stirring continuously till it becomes thick. Remove from flame and keep aside to cool down completely.
Put melted butter, cocoa powder in another bowl and mix it well till no lumps.
Put 1 cup of all-purpose flour, powdered sugar, salt, baking powder, vanilla essence, condensed milk and milk in separate bowl. Mix it well till no lumps.
Lastly add cocoa mixture, flour paste/mixture, roasted walnuts and Choco chips. Mix it well and make lumps free and smooth batter.
Grease the mould or cake pan with butter and drop the cake batter into the grease mould. Tab the pan so that the batter should evenly spread without any air bubbles.
Garnish with some roasted walnuts and Choco chips on top of the batter.
Bake in a pre-heated oven at 180 degree Celsius for 30 to 35 mins in the convection mode of a Microwave Oven.
Once baked, insert a tooth pick or knife just to see if it is cooked properly or not. If the Knife comes out clean it means the cake has cooked properly.
Remove the chocolate walnut brownie from the pan and after it cools a bit scratch the sides of the tin, invert it into cooling rack or tray and let it cool completely.
Slice and garnish Chocolate walnut brownie with chocolate syrup and serve.
Use roasted walnuts only to make brownie for better taste. I've used round cake pan but you can use any shape of cake pan to make brownie