Transfer chocolate mixture to a bowl and let stand until mixture cools, about 20 minutes.

Beat remaining 1 cup cream in a medium bowl until stiff peaks form. Fold into cooled chocolate mixture. Cover, chill at least 2 hours.

Meanwhile, make the brownies.

Position oven rack in the lower third of the oven. Preheat oven to 325 degrees F.

Butter an 8 x 8-inch baking pan.

Combine the butter, sugar, cocoa, and salt in a medium heatproof bowl and place the bowl over a pot containing about 1-inch of simmering water. Stir occasionally until the butter is melted and the mixture is smooth.

Remove the bowl from the pot and set aside to cool slightly.

Stir in the vanilla and add the eggs one at a time, whisking after each addition. Continue whisking until the batter becomes shiny and well blended.

Stir in the chocolate chips.

Spread evenly in the pan.

Bake for about 20 - 25 minutes or until a toothpick inserted into the center comes out clean.

Transfer pan to a cooling rack to cool completely.

TO ASSEMBLE

Cut 1/2 to 1-inch squares of the brownies and drop them into the parfait glasses. Top the brownies with a few spoonfuls of the mousse. Repeat until glasses are filled.

Top with whipped cream, if desired.