MIX OREO Pieces and butter; press 1/2 cup onto bottom of each of 24 (4-inch) springform pans (or onto bottom of 2 [4-inch] springform pans for trial recipe).
PULSE 3 qt. of the nuts (or 1 cup of the nuts for trial recipe), granulated sugar and salt in food processor until nuts are ground to medium-fine size. Add whole eggs, egg whites and flavorings; pulse until well blended. Add butter; pulse until blended. Stir in remaining nuts; spoon 3/4 cup over each crust. Cut each pear half into thin slices; fan over top of each tart.
BAKE in 300ºF-convection oven 35 to 40 min. or until filling is set and tops are golden brown. Cool completely. Run sharp knife around each tart to loosen from rim of pan. Remove rims and dust tarts with powdered sugar just before serving.