Preheat oven to 400°F. Roll out 1 pastry disk on floured surface to 6-inch round. Transfer to 4 1/2-inch-diameter tartlet pan with removable bottom. Press crust onto bottom and up sides of pan; trim overhang to 1/2 inch. Fold overhang in and press, forming double-thick sides. Repeat with remaining dough disks and 5 more pans. Chill crusts while making filling. Stir cream and next 5 ingredients in heavy medium saucepan over medium-low heat until sugar dissolves. Increase heat; boil until mixture bubbles thickly and color darkens slightly, about 6 minutes. Remove from heat; stir in walnuts. Place crusts on baking sheet. Divide filling among crusts. Bake tartlets until filling bubbles thickly and crusts are golden, about 25 minutes. Cool tartlets in pans on rack 5 minutes. Remove pan sides while tartlets are still warm. Serve slightly warm or at room temperature.