1. Heat oven to 375°F. Unroll pie crust on lightly floured work surface; roll into 12-inch round. Using 2 1/4-inch round cutter, cut 24 rounds, rerolling dough as necessary. Gently press rounds floured side down into 24 ungreased nonstick miniature muffin cups.
2. Sprinkle 1/3 cup of the pecans evenly into pie crust-lined muffin cups. In small bowl, beat brown sugar, butter, vanilla and egg with whisk just until smooth (do not overbeat). Spoon teaspoonful filling over pecans in each tartlet. Sprinkle with remaining 1/3 cup pecans.
3. Bake 12 to 15 minutes or until filling is set and crust is light golden brown. Cool 1 minute; remove from pans. Cool completely, about 30 minutes.
4. In small microwavable bowl, microwave Drizzle ingredients uncovered on High 30 to 60 seconds, stirring every 15 seconds, until melted and smooth. Drizzle onto tartlets.