Spray a 9-inch tart pan with non-stick baking spray and preheat oven to 325°F.

Combine vanilla wafer crumbs and sugar in a medium bowl. Add melted butter and stir until well combined.

Press the crumb mixture firmly into the bottom and up the sides of the tart pan. Use a measuring cup or glass for the bottom and your fingers for the sides.

Bake for 7 minutes, then remove from oven and let cool completely. You can refrigerate or freeze to speed up cooling.

In a small bowl, sprinkle gelatin over cold water. Stir to moisten and let stand for 5 minutes.

In a saucepan, whisk cornstarch and sugar. Add champagne and heat over medium heat, stirring constantly, until the mixture just begins to boil. Remove from heat.

Heat the gelatin mixture for about 10 seconds until melted, then whisk into the champagne mixture until smooth. Let cool to room temperature.

In another bowl, whip heavy whipping cream and powdered sugar until thickened.

Add mascarpone cheese and whip on low speed until incorporated, then increase to medium speed until the whipped cream thickens and holds its shape.

Carefully fold the cooled champagne mixture into the mascarpone mixture in two additions until well combined.

Spread the filling evenly into the cooled crust and refrigerate for 2-3 hours, or until firm.

Combine champagne, cornstarch, and sugar for the glaze in a small bowl. Microwave in 10-second increments until it boils and thickens, about 30-40 seconds. Let cool slightly.

Layer the sliced strawberries on top of the tart filling. Brush the cooled glaze onto the strawberries with a pastry brush.

Refrigerate the tart for 30 minutes to an hour, or until the glaze is cool, then serve.