Preheat oven to 375ºF (190ºC). Line a 9" (23 cm) square cake pan with parchment paper, overlapping the two ends for easy removal.
Base: Combine flour and icing sugar in a medium bowl. Cut in butter until mixture is crumbly. Press firmly into prepared pan.
Bake in preheated oven for 15 to 18 minutes, or until golden.
Filling: Spread jam on warm crust. Beat cream cheese and cream in small mixer bowl using an electric mixer on medium speed. Add white chocolate, beating until smooth. Mix well. Spread evenly over jam. Chill to set, about 1 hour.
Topping: Melt chocolate chips and butter together over low heat, stirring until smooth. Spread over filling. Chill until set.