To make chocolate brownie, preheat oven at 170° C. Line 9 inch square tin with parchment paper and grease it with little butter.
Sift flour, cocoa powder, salt together in a bowl. Keep aside until required.
In a large ceramic bowl add chopped chocolate and butter. In a little smaller heat resistant bowl add 1 Cup water. Arrange bowl of chocolate over water bowl. Heat over medium flame stir chocolate and butter with spatula to avoid sticking to the bowl. Keep on stirring until chocolate and butter is melted. Keep the melted liquid aside while you beat eggs.
In a bowl add eggs with vanilla, chocolate essence and sugar. Beat with Hand Mixer starting with speed level 2 gradually moving to higher speed. Beat until mixture turns light and creamy.
Add the cooled down melted chocolate to the eggs. Beat once again for 2 – 3 minutes using hand mixer at medium speed.
Once melted chocolate and egg mixture evenly combined fold in the sifted flour into the liquids.
Combine nicely using the spatula so that no lumps remain in the batter.
Add chopped walnuts and mix batter once again. Pour the brownie batter into the prepared tin. Bake for 35 minutes insert toothpick and test for doneness.
Bring tin out of the oven. Let brownie sit in the tin for 10 minutes. Then transfer to a wire rack and let it cool down for sometimes.
Once brownie cooled down cut into squares.
Serve Chocolate Brownie with vanilla ice cream and chocolate sauce.