Rinse the eggplant and trim off the ends. Thinly slice eggplant (about ¼ inch thick) and layer slices in a large bowl salting each layer. Cover with water, place a plate over the eggplant slices to keep them submerged and weight with a heavy object (a package of sugar, salt or a can) and let sit for 30 minutes.
Preheat oven to 425 degrees F and line 2 baking sheets with parchment paper. Grease generously with 2 tbsp. olive oil on each pan.
Drain the eggplant, rinse well and pat dry. Place on the baking sheets and drizzle extra olive oil over the top.
Bake for 20 minutes, flipping slices halfway through baking. Set aside.
Repeat with remaining eggplant slices.
Prepare the sauce and rice
Meanwhile, prepare a basic tomato sauce: heat 3 tbsp. olive oil in a deep skillet or sauce pan. Add onion and cook, stirring, for 5 minutes until translucent. Stir in minced garlic.
Pour in tomato passata and fresh basil leaves. Bring to a boil then lower to a simmer and cook partially covered for 1 hour.
Add salt to taste and stir in the frozen peas (no need to defrost them). Cook an additional half hour. Taste and adjust seasoning if necessary.
While the sauce is simmering, boil water in a medium sized sauce pan. Add salt and Arborio rice. Lower heat to a simmer, cover and cook for 17-18 minutes, until very al dente.
Drain well and transfer to a large bowl. Stir in the tomato sauce and grated Pecorino Romano cheese.
Assemble the timbale
Preheat oven to 350 degrees F. Lightly grease a rectangular (10 X 14inch) baking dish with olive oil and sprinkle 2 tbsp. of breadcrumbs evenly on the bottom.
Cover the bottom with a layer of eggplant slices (⅓ of the eggplant). Spread half of the rice over the eggplant. Top with the hard boiled eggs slices and half of the shredded mozzarella.
Top with another layer of eggplant and the remaining rice. Spread the remaining cup of sauce over the rice. Sprinkle the rest of the mozzarella over the rice.
Top with the remaining eggplant slices and sprinkle the rest of the breadcrumbs over the top.
Bake for 30 minutes until the casserole is heated through and the eggplant is golden. Let sit for 15 minutes before serving.
Notes
Substitutions and Variations-Peas in tomato sauce and hard boiled eggs are classic additions to Sicilian baked pasta or rice dishes. But if you are not a fan of these ingredients you may omit them. -For a non-vegetarian version of this dish, prepare a meat sauce as in this Sicilian lasagna recipe. -I love the layered presentation of timbale, however if you're in a rush you can prepare a simplified 'dump' version of this casserole. Cut the eggplant into cubes instead of slices and prepare as indicated in the recipe. Stir all the ingredients together: rice with tomato sauce; eggplant; hard boiled eggs and mozzarella; top with a layer of breadcrumbs and bake!StorageKeep leftovers refrigerated for up to 3 days.Make AheadPrepare the timbale a day ahead, refrigerate and bake the following day before serving.