A lot of porcelain/ceramic bowls will be oven safe by nature, so I would start with those. Ramekins tend to be around 100..250mL, but you can get them in 300..800mL range and up. The first thing you need to do is pick a size (by volume), and then you can search for styles of bowls by size. Anything that is 550mL and up seems to get called a <em>soup bowl</em> from what I can see.