Pulse flour, cold cubed butter, granulated sugar, and salt in a food processor until sandy. Add egg and vanilla, pulse until dough clumps. Form into a disc, wrap, and chill 30 minutes.

Preheat oven to 350°F (175°C). Roll dough ¼ inch thick on parchment. Cut out numbers using a stencil or freehand. Re-roll scraps as needed.

Transfer parchment to a baking sheet. Bake 12 to 14 minutes until edges are golden and centers firm. Cool completely on the pan.

Whip cold heavy cream, mascarpone, powdered sugar, and vanilla bean paste to stiff peaks, about 3 to 4 minutes. Keep chilled.

Place one cookie number on a platter. Pipe cream dots over the surface, then layer half the sliced strawberries on top. Top with the second cookie, pressing gently.

Pipe remaining cream on top and arrange the rest of the strawberries and whole berries. Brush with warm jam mixture if using. Serve within 2 hours.