Unfold and stack piecrusts on a lightly floured surface. Roll into 1 (12-inch) circle. Fit piecrust into the bottom and up the sides of a 9-inch deep-dish tart or quiche pan (about 1 1/2- to 1 3/4-inches deep). Prick bottom and sides of piecrust with a fork. Freeze 10 minutes.
Line piecrust with parchment paper; fill with pie weights or dried beans.
Bake at 425° for 10 minutes. Remove weights and parchment paper; bake 12 to 15 more minutes or until crust is lightly browned.
Pour Tangy Lemon Tart Filling into piecrust; top with Lemon Meringue Pie Filling. Cover with plastic wrap, placing directly on Lemon Meringue Pie Filling. Chill at least 4 hours.
Beat cream and sugar at medium speed with an electric mixer until soft peaks form. Dollop on top of tart. Garnish, if desired.