Lovely picture, thanks. I'm besotted already, and I echo CaroleB's enquiry ...
It may indeed be a fritatta pan - though I'm not sure it would be so neccessary for a traditional frittata, as they are usually shallow enough to be teased with a fork and flipped with the aid of a spatula or "a la pancake" without too much stress ...
I suspect it's intended for spanish tortilla (i.e. a "cake" of omlette & potato). Tortilla is deep, dense and (ideally) served slightly runny in the centre - and therefore a pain in the proverbial to flip manually, normally requiring use of a plate as an intermediate part of the turning procedure.
You can get a similar hinged omelette/crepe pan here
Omelette and Crêpe Pan- Lakeland, the home of creative kitchenware but it is simply no comparison on looks, depth or curvature of the base (again, this suggsts tortilla to me). A purpose designed hinged tortilla pan is here
LaTienda.com - 2-Piece Tortilla Espanola Pan - Heavy Duty & Non-stick - but again, the terracotta just looks sooo much nicer!
I want the terracotta one! tell me where I can buy it & what it costs!!