First, wash and prep all (or most) of your veggies. Cube the eggplant, dice the onions, chop the tomatoes, peel the garlic, slice the zucchini into half moons, and strip the basil from their stems.
Next, put a large soup pot on medium high heat on the stovetop, adding a generous amount of olive oil (about 1/3 cup).
Test to see if the oil is hot by adding a cube of eggplant. If the oil sputters when a cube of eggplant is added, add all of the eggplant and stir. Stir occasionally with a wooden spoon for about 5 minutes.
Next, add the diced onions and a little more oil, salt and pepper. Cook for 15 minutes, stirring occasionally until the eggplant is cooked down and the onions are translucent.
Next, add the chopped tomatoes and stir, lowering the heat to medium. Stir occasionally for another 10 minutes.
Finally, add the whole garlic, zucchini, and basil and give a good stir, adding the remaining olive oil and any additional salt and pepper needed. Lower to a low-medium heat and let simmer until all of the vegetables cook down and release their juices.
After about 20-25 minutes of simmering, taste your ratatouille, adding additional basil, salt or pepper if desired.
Serve steaming hot in bowls, ideally with a fresh loaf of bread to share. Bon appétit!