Just for 2 of us, so it filled a 2-1/2 qt. casserole pan just perfectly, but you can easily use as many veggies as you want to make it larger. I did this once before with leftover "regular" Ratatouille and it was so good, that I decided to make it this way deliberately!
You can prepare ahead and heat about 1/2 hour before dinner, if you want.
ROASTED & BAKED RATATOUILLE
1 small-medium regular eggplant (or 2-3 Japanese)
1 large cucumber (or zucchini)
6-8 Roma tomatoes and a handful of cherry or grape tomatoes
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extra-virgin olive oil and HERBS (dried rosemary ~ basil ~ oregano)
Kosher, sea or pink Himalayan salt
NOTE: I used each of these for each "bag" of veggies that I tossed with the olive oil ~ so you can just shake as much as you want into each bag ~ probably about 1/2 tsp. salt into each bag, but I like herbs so I probably used at least 1 tsp. herbs in each bag. I drizzled the olive oil in but according to how much was in there. There was more eggplant than cucumber ~ and more cucumber than tomatoes ~ so maybe 1 TB olive oil with the eggplant. But the time I did the tomatoes, maybe only 1 tsp. since there was already oil in the bag.
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Preheat oven to 420. Line a large rimmed baking sheet with foil and spray with non-stick baking spray (I like to use olive-oil or canola oil non-stick spray). Set aside.
Prepare veggies:
EGGPLANT: I didn't peel first, but cut off the top. Then cut in half, and quarters. Cut into small slices or cubes. Put into a large baggie (I used a grocery bag ~ make sure it doesn't have a hole in the bottom!) Drizzle some olive in there ~ then sprinkle salt & herbs over it. Hold tightly closed and shake. Then squish it around in your hand until all the eggplant is coated well. Scatter it around evenly on the prepared pan.
CUCUMBER: Cut in half, then into quarters. It's easiest to slice off the seeds this way. Then cut into about 1/2" to 1" pieces and stick into that same bag. (If you're using ZUCCHINI ~ just cut it the same way). Same thing: Drizzle a little oil ~ then salt & herbs. Shake & squish ~ scatter over the eggplant pieces on the baking sheet.
TOMATOES: Romas I cut in quarters, then large pieces. I poked holes in the cherry / grape (or cut in half if they were bigger), so they didn't burst in the oven. Now, those go into the same bag ~ same oil & herbs ~ scatter on the eggplant & cucumber and fill in the gaps.
Roast @ 420 for about 20-25 minutes. They should just be soft and shriveled, but not necessarily "burnt" (a little charred is fine). Let them rest in the pan for a few minutes (too hot and the cheese will melt before you mix it in there completely).
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Balsamic vinegar (maybe 1 TB)
fresh grated Italian cheese (about 1/2 - 3/4 cup) ~ whatever you like (I used a blend here)
Spray your casserole pan with non-stick spray. If you're using foil to cover it in the oven, spray the underside of the foil too, so it won't stick to the cheese.
Put all the roasted veggies into a medium bowl. Add the Balsamic vinegar and cheese ~ mix it all up with a wooden spoon ~ put into the prepared casserole dish.
Put into a pre-heated 350 oven (COVERED) for about 20-30 minutes ~ or until the cheese is all melted and it's hot throughout. You might need to uncover for the last 5-10 minutes.
NOTE: If you're using CUCUMBERS, they'll release water during baking ~ you'll probably want to put another 1/4 cup shredded cheese on top about 10 minutes before taking out of the oven.