This is a super quick (25 minutes including prep time) appetizer dish that takes advantage of some of the best flavors of Summer. Serve with pita chips or thick veggie slices. Inspired by How Sweet Eat's Hot Caprese Dip.
Preheat your oven to 375. Wash the core the tomatoes, and then squeeze out all the juice and seeds to reserve for another use. Roughly chop the tomatoes and set aside. Tear up or dice the mozzarella into chunks, and also set aside. Remove the chard stems and dice, and then stack the washed chard leaves and roll them up. Cut into 1/2" ribbons. Bring the oil over medium-high heat and sauté the chard stems for 3-5 minutes (pop one in your mouth- you want it to still have a little crunch but not be too tough) and then add in the chard leaves for 2-3 minutes longer. Same thing here-- try a bite of a chard leaf and make sure it's not too tough.
Scatter about 2/3rds of the cheese or beans and most of the tomatoes on the bottom of your casserole or oven-safe serving dish. Crack on some salt and pepper. Nestle all the chard stems and leaves on top, and tear up 2/3rds of the basil on top of that. On the top layer, add the rest of the tomatoes, then the cheese or beans, then the basil. Use some more salt and pepper all over. Pop it into the oven for 15 minutes, and maybe a minute or two under the broiler at the end to really toast the cheese.
This dish can have some water at the bottom (the juice that cooked off the tomatoes and the chard leaves), so serve it with thick slices of toasted pita or veggie chips (kohlrabi slices work great.)