Bake shells according to package directions. Cool; push down middles to form a cavity. Set aside.
Stir together sugar, cornstarch and salt in saucepan. Over medium-high heat, stir in milk. Add ginger; bring to boiling, stirring constantly; cook for 1 to 2 minutes or until mixture is thickened.
Beat egg yolks in small bowl until light colored and thickened. Stir in small amount of hot milk mixture. Stir yolk mixture back into saucepan; cook, stirring constantly, over medium heat for 2 minutes or until pastry cream thickens and registers 160 degrees F on instant-read thermometer. Stir in butter and vanilla until melted.
Strain pastry cream through fine-mesh sieve into medium-size bowl. Place plastic wrap directly on surface. Refrigerate until cool.
Peel pear; cut in half lengthwise; core. Cut each half crosswise into thirds. Place in small bowl with the water and the lemon juice.
Equally divide pastry cream among 6 pastry shells on 6 dessert plates. Slice each pear piece crosswise as thin as possible. Fan out and place on top of pastry cream in each tartlet.
Melt apple jelly in small saucepan over medium heat. Brush over pears and tartlet shells. Makes 6 servings.