In a large bowl, cream butter and cream cheese until smooth. Gradually beat flour into creamed mixture. Shape into a disk; wrap in plastic. Refrigerate 1 hour or until firm enough to handle.
Divide dough into 12 portions. Roll each portion into a 5-in. circle; transfer to 12 ungreased 4-in. fluted tart pans with removable bottoms. Trim crust even with edges. Refrigerate 20 minutes. Preheat oven to 375°.
Meanwhile, in a large bowl, whisk the first 6 filling ingredients. Pour into tart shells; arrange pecans over tops. Bake 25-30 minutes or until centers are just set (mixture will jiggle). Cool on wire racks. If desired, serve with ice cream. Refrigerate leftovers.