Heat oven to 425 degrees F. Grease and flour six 6-ounce ramekins or custard cups.

In small saucepan, melt butter and chocolate over medium heat, stirring until smooth. Let cool slightly.

In medium-size bowl, beat sugar and egg yolks with mixer about 4 minutes until very light in color. Beat in rum and vanilla until blended. With mixer running, add chocolate mixture in thin stream. Stir gently with wooden spoon until no light streaks remain.

Sift half the flour over the batter; gently fold in. Repeat with remaining flour until blended. Divide evenly among prepared dishes, about 1/2 cup per dish. Place dishes on a small baking sheet.

Bake at 425 degrees F for 20 minutes or until center registers 150 degrees F on instant-read thermometer. Transfer to wire rack; let stand 1 minute. Run thin metal spatula around top edge of each dish. Gently tap edges of dishes on counter to loosen sides. Top one dish with small dessert plate; quickly invert and rap on counter to release the cake from the dish onto plate. Repeat with remaining cakes.

Drizzle a little Raspberry Sauce on each plate around the cake. Serve warm with remaining sauce on the side. Raspberry Sauce: Combine 1 package (10 ounces) frozen raspberries in syrup and 1 tablespoon confectioners' sugar in a small food processor or blender. Puree until smooth. Press through sieve to remove solids. Refrigerate sauce until just before serving.