For cake: Combine all ingredients in a large mixing bowl. Beat till smooth. Pour into two well greased and floured 8" cake pans.

Bake at 350° for about 30 minutes, or until a toothpick comes out clean. Let cool in pans for 5-10 minutes, then invert onto cooling racks. When completely cool, use a long knife to cut off the rounded tops of the cakes.

For mousse: Combine gelatin and cold water in a small glass bowl. Let sit for about a minute till dissolved, then stir to mix. Add the boiling water (I boiled it in the microwave), and stir till it is nice and melted. Set aside.

Beat the cream till soft peaks form. Whisk together the cocoa and the sugar, and sift to remove any lumps if needed. Add to the whipped cream with the vanilla and the gelatin mixture.

Continue beating till everything is mixed well. Cover and chill for about 30 minutes.

Ganache: Place chips and cream in a glass bowl. Melt in the microwave, stirring often. Whisk till totally smooth. Let cool to thicken.

Place one layer of the cake on a serving plate. Spread the chocolate mousse evenly over the top. Sprinkle with half of the Heath bits. Top with the second cake layer. Carefully pour the ganache on top of the cake. Use a spoon to spread it towards the edge, and just let the excess drip down the sides. You may not need all the ganache.

Sprinkle with the remaining Heath bits just before serving. Chill any leftovers.