Preheat oven to 325 degrees F.

Line an 8x8 baking dish with parchment paper, leaving some overhang to easily pull the mousse brownies out of the pan for cutting. Spray the parchment well with non-stick spray.

With an electric mixer, beat the eggs at medium speed until fluffy and light yellow, add the sugar and beat until combined. Add remaining ingredients, and mix to combine.

Pour the batter into the prepared baking dish and bake for 30-35 minutes. A toothpick inserted should come out with just a few crumbs. Do not over bake. Allow to cool in the baking dish.

In a small bowl, combine the gelatin and water. Set aside to bloom for at least 10 minutes.

Bring a pot of water to a low boil. Add the chocolate to a heat proof bowl that fits over your pot. Place the bowl of chocolate over the pot and stir until melted. Remove bowl from heat.

In a small saucepan, bring 1/4 cup of the cream for a boil. Stir the gelatin mixture into the hot cream until fully dissolved. Remove from heat.

Whisk the cream/gelatin mixture to the melted chocolate pouring in about 1/2 of the mixture at a time. Whisk until smooth.

In another mixing bowl, use an electric mixer to beat the remaining 1 cup of heavy cream until soft peaks form. Once the chocolate mixture has cooled, carefully fold it in with a rubber spatula.

Pour the mousse over the brownie layer and use the rubber spatula to smooth out the top. Refrigerate for at least 6 hours.

To serve, lift the mousse brownies from the pan using the parchment paper edges, sprinkle with a little cocoa powder (optional), run a knife through cold water and cut into square bars. You may need to wipe down the knife and run it under cold water again between slices for a clean slice look.