Step 1

Salt the eggplant: Arrange the eggplant rounds on a large tray or cutting board and sprinkle each slice on both sides with kosher salt. Set aside for a few minutes while you prepare the bread.

Step 2

Prepare and broil the bread: Set a rack in the middle of your oven and turn on the broil function. Put the bread on a cutting board and position your non-dominant hand on top. Using a sharp knife, carefully cut the ciabatta in half through the center to make two long halves. Open the two halves and place on a baking sheet with the crust-side down and the cut-side facing up. Drizzle generously with olive oil. Put the bread in the heated oven on the middle rack and watch for the top to turn crispy and golden brown around the edges, about 1-2 minutes. Remove from the oven.

Step 3

Bake the eggplant: Turn the oven to 400°F. The eggplant should have “sweat” a bit from the salt, with beads of water appearing on the surface. Use a paper towel to wipe the eggplant well, removing excess salt and water. Arrange the eggplant slices on a large, lightly oiled sheet pan and brush the tops with olive oil. Bake on the center rack of the heated oven until the eggplant has softened and turned slightly golden brown, about 20 minutes.

Step 4

Assemble: Spread the pesto over the toasted side of the bread, followed by 3/4 of the spaghetti sauce. Top with the roasted eggplant slices, and finally, top each eggplant slice with a slice of mozzarella. Dollop each mozzarella slice with red sauce.

Step 5

Bake: Slide the sheet-pan with the assembled eggplant sandwiches on the center rack of the oven. Bake until the mozzarella is melted and has gained some color, about 10 minutes. Remove from the oven and add the grated Parmesan on top. Return to the oven for a minute or two for the Parmesan to warm through.

Step 6

Slice and serve: Slice each half of the bread into 5 to 6 pieces, with each piece having its own eggplant and cheese stack. Garnish with fresh basil, if using, and serve.