Line a sieve with muslin or cheesecloth and put the ricotta in there, setting it over a bowl.

Put it in the refrigerator for 2 hours or until most of the ricotta liquid has drained off.

Put the flour in a bowl with the cornmeal, salt, sugar, bicarbonate of soda, and baking powder.

Add the butter and rub it in with your fingers.

Make a well in the middle and pour in the buttermilk.

Use a butter knife to mix the buttermilk into the dry ingredients until you get a soft dough.

Add the ricotta and blend that in too.

Dust a worktop with flour and turn out the dough, shaping it into an 8x6-inch rectangle.

Fold the top third down into the middle and repeat twice more, so you end up with an inch-thick piece of dough.

Press the dough into an 8x6-inch baking dish.

Wrap in plastic wrap and chill for 20 minutes.

Put the tomatoes and corn kernels in a 12x8-inch baking dish.

Add the vinegar, most of the oil and some salt and pepper, and stir.

Preheat the oven to 350°F.

Heat the rest of the oil in a skillet, then sauté the onions for about 12 minutes.

Add the garlic and cook for several minutes, then mix in the thyme leaves and some salt and black pepper.

Spoon the onion mixture over the tomato mixture.

Now lay the dough on a floured worktop and cut it into squares or circles using a sharp knife.

Arrange the dough pieces over the vegetables.

Sprinkle the parmesan on top, and bake for 45 minutes or until bubbling and golden brown on top.

Let the savory cobbler sit for 10 minutes before serving, since the tomato mixture will be scalding hot