Preheat oven to 375°F. Combine graham cracker crumbs and sugar in a bowl.
Mix in egg yolk and vanilla extract, then stir in melted butter until mixture resembles wet sand.
Press crust firmly into bottom and slightly up sides of a 9-inch springform pan.
Bake crust for 8 minutes, remove, and cool completely.
Reduce oven temperature to 350°F.
Beat softened cream cheese until creamy; add sour cream, cornstarch, sugar, and vanilla extract, mixing until smooth.
Fold in vanilla bean seeds until well combined.
Spread cheesecake batter evenly over cooled crust.
Bake for 30-35 minutes until edges are set and center jiggles slightly. Cool completely.
Beat whipping cream with vanilla and confectioners’ sugar until soft peaks form, then stiffer peaks.
In separate bowl, beat cream cheese until fluffy; add melted white chocolate and mix until smooth.
Gently fold whipped cream into white chocolate mixture without deflating.
Spread white chocolate mousse over cooled cheesecake layer.
Beat whipping cream with confectioners’ sugar and vanilla bean seeds until soft then slightly stiffer peaks form.
Spread sweetened whipped cream evenly over mousse layer.
Refrigerate cheesecake at least 1-2 hours or overnight before serving.
Slice and serve chilled for best flavor and texture.