Position an oven rack at the lower third position of the oven. Preheat the oven to 425˚ F.
Lightly oil a 9-inch baking dish with olive oil. Note that glass plans usually warn of baking at high temperature, so use a ceramic, or non-reactive metal pan or skillet to be on the safe side.
In a large bowl, combine the cherry tomatoes, onions, garlic, pepper flakes, salt and pepper. Splash the olive oil all over and stir gently to distribute the ingredients evenly. Transfer into the prepared baking dish. Set aside whilst preparing the cobbler.
Place the dry ingredients in the bowl of a food processor, including the cheese, and pulse to combine. Add the butter and pulse until the mixture looks like coarse bread crumbs. Add the egg and buttermilk and pulse a few times to create a sticky dough.
Drop dollops of the biscuit dough evenly on top of the cherry tomatoes. Each dollop should measure a generous 1/ 8 cup. Pat the dough out slightly but leave space between the cobbles as they will expand during baking.
Bake for 20 – 25 minutes until the biscuits are golden and cooked through; and the tomatoes and onions have softened. I actually don’t mind a little texture remaining in the onions. If you want them perfectly soft, chop them a bit finer.
Let sit for about five minutes before serving. If the tomatoes are juicy, there will be liquid in the bottom of the dish. I just use a slotted spoon or spatula to serve, which strains it well enough.