Definitely a tart as in the tarte au citron or chocolat category if you're v. posh or live close to a cross-channel ferryport.
In the UK we tend to make small individual tarts in a bun tin and usually it's jam/preserves instead of the whole fruit a la Mr. Kripling (on purpose
). Flans are definitely sponge made with an extra egg so it's firmer than cake sponge
A home made variation
So what you have there is a German plum tart with a Michelin star