How to Make It
Heat 1 cup oil in a large saucepan over medium-high. Add onion and 1/2 teaspoon salt. Cook, stirring often, until onions are softened and just beginning to brown, 6 to 8 minutes. Add pomodori pelati and passata di pomodoro. Using a heatproof spatula or wooden spoon, press to flatten tomatoes, breaking into large chunks. Bring to a boil over medium-high. Reduce heat to medium-low, cover, and cook, stirring every 10 to 15 minutes to ensure sauce is not sticking, until flavors meld, about 1 hour.
Uncover tomato sauce. Cook over medium-low, stirring occasionally, until sauce tightens up and reduces to about 5 1/2 cups. (Oil will rise to the top and shimmer on the surface.) Remove from heat, and let cool at room temperature 1 hour. Add 1 tablespoon salt; stir to incorporate salt and oil, creating a thick, glossy sauce. (The bottom of your serving bowls will have a thin layer of red oil that’s perfect for soaking up with bread.) Set sauce aside.
Preheat oven to 400°F. Heat a large grill pan over medium-high. Brush pan with remaining 1 tablespoon oil to prevent sticking. Grill eggplant planks in batches, turning often, until tender and grill marks appear, 8 to 12 minutes.
Spread 1 cup tomato sauce in bottom of a 12-inch stainless steel skillet. Top with a single layer of eggplant (about 6 pieces); sprinkle with 1/4 teaspoon salt, 2 tablespoons torn basil, and half of the mozzarella. Spoon 1 cup sauce over top, and sprinkle with 1/4 ounce Parmigiano-Reggiano. Repeat layers once, beginning with eggplant and ending with Parmigiano-Reggiano. Top with remaining eggplant slices, remaining 1/4 teaspoon salt, and 2 tablespoons basil. Spread remaining sauce over top, completely covering eggplant. Sprinkle with remaining 2 tablespoons basil and 1/4 ounce Parmigiano-Reggiano. Cover skillet tightly with aluminum foil, and place on a rimmed baking sheet.
Place skillet on baking sheet in preheated oven, and bake until edges are bubbling (lifting up foil to check), about 1 hour. Uncover and bake until sauce tightens up but doesn’t dry out, about 30 minutes. Sprinkle with remaining 1/4 ounce Parmigiano-Reggiano, and bake until melted, about 3 minutes. Let cool at least 20 minutes before serving. Garnish with whole basil leaves.
Get LoPresti’s tomato passata recipe here.