1Heat oven to 400°F. On lightly floured surface, unfold pastry sheets, pressing fold marks flat and sealing any tears. Measure diameter of soup plate or bowl to be used as serving dishes. Using small sharp knife, cut 12 tree shapes from pastry, about 4 to 5 inches tall and wide, to fit in soup plate. Reroll cut dough to 1/4-inch thickness as necessary to cut all trees.
2On ungreased cookie sheets, arrange pastry trees 1/2 inch apart. Brush with egg. Bake about 8 minutes or until puffed and golden brown.
3Meanwhile, in 4-quart Dutch oven, melt butter over medium heat. Add celery and onions; cook 5 to 7 minutes, stirring occasionally, until crisp-tender but not browned. Stir in flour until no lumps remain. Slowly add broth, half-and-half and wine, stirring constantly. Heat to boiling, stirring constantly; cook 2 to 3 minutes or until slightly thickened.
4Stir in mixed vegetables, chicken, tarragon, salt and pepper; cook 2 to 3 minutes longer or until hot. Remove from heat. Spoon about 1 1/4 cups chicken mixture into each soup plate. Top with pastry tree.