In a medium bowl, beat together cheeses, butter, cream, flour, lemon zest and juice, and salt with a mixer at medium speed until combined. Add eggs, one at a time, beating well after each addition. Add chives, beating until incorporated. Divide mixture among prepared Quiche Crusts, spreading evenly. Place quiches on a rimmed baking sheet.
Bake until filling is set, 15 to 20 minutes. (The surface will puff, crack, and then deflate.) Let quiches cool slightly before carefully removing from tartlet pans.
Divide Ratatouille among quiches, spreading to cover filling.
Garnish with basil, if desired.
Recipe by TeaTime Magazine at https://teatimemagazine.com/ratatouille-quiches/