PREHEAT oven to 375° F. Grease 9-inch tart pan with removable bottom.
MELT semi-sweet morsels and butter in medium, heavy-duty saucepan over lowest possible heat. When morsels begin to melt, remove from heat; stir. Return to heat for a few seconds at a time, stirring until smooth. Remove from heat. Stir in graham cracker crumbs and pecans. Press onto bottom and up sides of prepared pan. Freeze for 5 minutes.
BAKE for 8 minutes. Cool completely in pan on wire rack.
HEAT cream in small saucepan over medium heat until it just begins to boil. Turn off heat. Add premier white morsels; whisk until smooth. Remove from heat. Reserve 2 tablespoons mixture in small resealable plastic bag.
BEAT cream cheese and 1/3 cup sugar in large mixer bowl for 2 minutes. Stir in
remaining white morsel mixture from saucepan. Pour into crust. Refrigerate for 30 minutes.
PLACE raspberries and juice in blender container or food processor. Cover; blend or process until crushed. Strain through a strainer into a small saucepan. Discard seeds. Add remaining sugar. Combine lemon juice and cornstarch and add to raspberry mixture. Cook over medium heat for 5 to 6 minutes or until thickened; do not boil. Cool to room temperature.
PLACE strawberries in raspberry mixture to coat. Remove with slotted spoon; arrange over top of tart. Spoon raspberry mixture over tart. Reheat reserved white morsels mixture in microwave oven on MEDIUM-HIGH (70%) power for 15 to 20 seconds; knead. Cut small hole in corner of bag; drizzle over tart. Refrigerate for at least 1 hour. Remove side of tart pan and place on serving platter before serving.