Line the bottom of 9x13” pan with parchment paper. Line with pie crusts, cutting excess dough with a sharp knife. Ruffle top edges of dough by pinching every 1/2 inch or so together with fingers and indenting with a thumbprint.
In a large bowl crack eggs, whisk in half and half, flour, salt and pepper. Toss in 3/4 cup of basil leaves. Pour into prepared pie crust.
Arrange tomatoes, 3/4 of the burrata and 3/4 of the prosciutto atop egg mixture. Use a knife to gently tuck some of the toppings below the surface of the quiche.
Bake for 50 minutes, the top with remaining burrata and prosciutto. Return to oven and cook 10-15 minutes, or just until the center of the quiche is set. Remove from oven and cool for at least 20 minutes. Top with fresh basil leaves. Serve warm, or at room temperature.