Bake puff pastry shells according to package directions.
In a medium saucepan over medium heat, melt butter and saute onions until tender, 3-5 minutes. Stir in flour and cook 1 minute. Increase heat to medium high. Slowly whisk in chicken broth. Let the sauce come to a boil to thicken. Reduce heat to medium low and stir in cream, poultry seasoning, thyme, salt, pepper, turkey, and vegetables. Keep warm on the stove top until ready to serve.
To serve, remove the center of a puff pastry shell and pour in the mixture.