Preheat oven to 350 degrees F. Line a 13x9 inch pan with nonstick foil or line with regular foil and spray with cooking spray.

In a mixing bowl, combine the crushed cereal and buttermilk. Let stand for 5 minutes to soften cereal. Add oil, egg, brown sugar and vanilla and stir until very well mixed. Stir in cocoa, baking soda and salt and (again) mix well. Finally, add the flour and stir just until mixed. Stir in chocolate chips.

Pour cake batter into pan and smooth it with a spatula so it's flat. Bake for about 25 minutes or until cake springs back when touched.

Let cool for 10 minutes or let cool completely and chill (hearts are a little easier to cut when cold.

Using a large heart shaped cookie cutter, punch out as many hearts as you can.