Preheat oven to 350 F.
Line a jellyroll pan with parchment paper.
Sift together flour and cornstarch and set aside.
Whip the 2 separated egg whites with cream of tartar until stiff peaks are formed; reserve. Warm 4 eggs in their shells in hot water for 2 minutes. Whip the 4 eggs with the 2 separated yolks plus additional yolk on high speed with sugar and vanilla until thick and pale. Fold in flour, and then fold in whites in two additions.
Spread batter evenly onto baking pan and bake for 15-18 minutes.
Allow to cool.
Line sides of an 8-inch pan with parchment. Cut a disc of sponge cake to line the bottom.
Heat white wine with lavender to infuse the flavour.
Strain out lavender (or leave in for colour).
Soften gelatin in 2 Tbsp cold water and set aside.
Over a pot of simmering water, whisk together egg yolks, sugar, lemon juice and wine until doubled in volume and whisk leaves a ribbon when you lift it.
Remove from heat and stir in gelatin.
Whisk in mascarpone cheese and pour into springform pan.
Let set for 4 hours before unmolding.
Remove springform pan and parchment. Sides can be coated with graham crumbs or left plain and tied with a ribbon for a special occasion. Garnish top with fresh lavender flowers or berries. Serve.