Brownies

3/4 cup cocoa
1/2 tsp baking soda
2/3 cup butter, melted and divided
1/2 cup boiling water
2 cups sugar
2 eggs
1 1/3 cups flour
1 tsp vanilla essence
1/4 tsp salt
1 cup chocolate chips

Preheat oven to 180C bake. Grease two 20x20cm square pans. Combine cocoa and baking soda, then blend 1/3 cup of melted butter. Add boiling water and stir until mixture thickens. Stir in sugar, eggs, and remaining 1/3 cup melted butter, stirring until smooth. Add flour, vanilla and salt and stir until mixed well. Stir in chocolate chips. Pour into the two pans and bake for 30-35 minutes. Cool in pans and then sprinkle with icing sugar.