For the batter:
Whisk together the milk, creme fraiche, and eggs until well beaten and smooth. Add in the flour until just combined, a thin batter will form quickly. Set aside.
Brush both sides of eggplant and zucchini slices with olive oil. Sprinkle with sea salt and cook on grill pan or in oven (375° F) for 4-6 minutes, turning halfway through.
Prepare a 9” cast iron skillet with a generous amount of olive oil over medium heat.
Arrange the tomatoes, eggplant and zucchini in alternating layers in the cast iron skillet and let cook undisturbed for about 3 minutes more.
Remove from heat and pour the prepared batter from the side so some vegetables are still on the surface.
Drop the ricotta in 1/4 cup increments evenly across the top.
Distribute most of the basil on top of the mixture and the sides while pulling away from the skillet.
Remove from oven and serve with remaining basil on top.