Prepare the Crust

1. Combine vanilla wafer crumbs, sugar and melted butter.
2. Grease a 9.75 by 4.25 inch rectangular tart pan, then press the crumbs into the bottom and up the sides of the pan. Set aside.

Make the Filling

1. In a small bowl, sprinkle gelatin over cold water. Set aside for about 5 minutes.
2. Add champagne, cornstarch and sugar to a sauce pan and heat on medium-high until champagne is hot and just starting to simmer around the edges. Do not boil.
3. Heat gelatin for about 10 seconds, until melted, then whisk gelatin into champagne until smooth. Remove from heat and set aside to cool and begin to thicken. (I put it into another bowl and then in the fridge to speed cooling – about 15-20 minutes)
4. In another bowl, whip heavy whipping cream until it starts to thicken.
5. Add powdered sugar and whip until stiff peaks form.
6. Fold the mascarpone cheese into the whipped cream.
7. Carefully fold cooled champagne mixture (it should be thickened and jiggly, but not firm yet) to mascarpone cheese mixture and mix until combined.
8. Spread mixture evenly into crust.

Add the Toppings

1. Layer sliced strawberries onto of tart filling.
2. Combine champagne, cornstarch and sugar for the glaze in a small bowl. Microwave in 10 second increments until thickened, about 20-30 seconds.
3. Brush glaze onto strawberries with a pastry brush.
4. Refrigerate tart until firm, about 3-4 hours.