Directions

1. In a medium mixing bowl, mix the flour, cocoa, white sugar, baking soda, and salt.
   
2. Add the lemon zest, lemon juice, vanilla, vegetable oil, and water. Mix thoroughly to achieve a creamy batter. Mix in the chocolate chips.
   
3. Pour into a greased 9x9-inch baking dish, and bake in a 350-degree oven for 35 to 45 minutes.
   
4. To make the frosting, combine the melted butter, cocoa, sugar, milk, and vanilla in a small mixing bowl. Whip until smooth.
   
5. When the cake has cooled, spread the frosting on the top.
6. Serve warm or cold.