Position knife blade in food processor bowl; add whole almonds, 1/2 cup sugar, and flour. Process until finely ground. Add softened butter and egg. Process until smooth and blended; set aside.
Roll 1 piecrust to a 14" circle on a lightly floured surface. Place in a 9" pieplate, allowing edges to hang over rim of pieplate.
Spread reserved almond mixture in bottom of pastry. Spoon chopped pear over almond mixture. Fold edges of pastry loosely over filling. (Pastry will not cover tart completely.) Sprinkle sliced almonds and 1 tablespoon sugar over filling.
Bake at 350° for 55 minutes or until golden. Cool on a wire rack.