Preheat your oven to 425°F (220°C). Toss the diced eggplant with 2 tablespoons of olive oil, salt, and pepper. Spread evenly on a baking sheet and roast for 20 minutes, flipping halfway through, until golden and tender.
Sauté the Aromatics
In a large skillet or heavy-bottomed pot, heat 1 tablespoon of olive oil over medium heat. Add the diced onion and garlic, cooking until softened and fragrant, about 3 minutes.
Toast the Rice
Add the Arborio rice to the pot and stir for 2-3 minutes, letting it absorb the oil and toast slightly. Don’t let the rice brown.
Deglaze with Wine
Pour in the white wine, stirring until it's mostly absorbed by the rice.
Cook the Risotto
Add the warm vegetable stock - begin by pouring in one ladleful at a time. Pour in a ladle of stock and stir until all the liquid is absorbed. Then, pour in another ladle of stock and repeat the process. Continue this until the rice is creamy and cooked al dente, about 20 minutes.
Add Lemon and Eggplant
Stir in the roasted eggplant, lemon zest, and lemon juice. Mix well to distribute the flavors.
Finish with Butter and Cheese
Stir in the Parmesan cheese and butter for a rich, creamy finish. Season with salt and pepper to taste.
Garnish and Serve
Serve the risotto immediately, garnished with fresh parsley, additional Parmesan cheese, and a sprinkle of lemon zest if desired.