How to Make It
Preheat the oven to 325°. Lightly butter two 4-by-1 1/4-inch round fluted tartlet pans with removable bottoms. Dust the molds with unsweetened cocoa powder, tapping out any excess cocoa.
In a small saucepan, melt the butter and chocolate over low heat. Remove the melted chocolate from the heat and let cool slightly. In a medium bowl, whisk the egg with 6 tablespoons of the sugar until blended. Add the melted chocolate and stir in the flour and salt. Pour the batter into the tart pans.
In a medium bowl, beat the cream cheese with the remaining 2 tablespoons of sugar until smooth. Add the egg yolk and vanilla and beat until smooth. Spoon half of the cream cheese batter over the chocolate batter in each tart pan. Using a fork, decoratively swirl the batters together in 3 strokes.
Bake the brownies for about 35 minutes, or until lightly browned and slightly puffed, but not completely set in the center. Let cool on a wire rack for 15 minutes before unmolding. Serve warm with whipped cream.