Mix flour, sugar, 2TB cocoa, baking powder and salt in 8x8" baking pan. Mix in milk, oil and vanilla with a fork until smooth. Stir in nuts (optional). Spread evenly in 8x8" pan (I use 8x11" pan to reduce overflow of sauce!). Sprinkle with brown sugar and 1/4 cup cocoa. Pour very hot water over batter (hot tap water is fine). Bake at 350 degrees for 35-40 minutes. Serve straight from the oven. Top with ice cream.