Vintage metal cake mold or pudding mold, 6 1/2" overall diameter x 4 1/2" tall. Love the fluted round shape, and it'll be easy to cook evenly since it's a ring mold.
This one is not marked that I could see - it looks European to me, possibly Portugal or Germany?
Nice and clean inside and out, with shiny tin inside, and a slightly darkened patina on the outside. So pretty, I'd display this on open shelving and use it as a canister!