prepare 8" baking pan. Whisk together dry ingredients. Melt chocolate and butter together. Whisk in sugar, then eggs one at a time. Stir in the dry ingredients. Beat together softend cream cheese, egg yolk, sugar and 1/2 t vanilla until smooth. Pour half of brownie batter into pan. Spoon in cream cheese mixture, cover with the remaining batter. Run a knife or skewer through the batter to swirl in the cream cheese. Bake @ 325 degrees for 50 - 60 minutes until a toothpick inserted in the center comes out with a few moist crumbs clinging to it.