Unflavored gelatin

I'm thinking that you are looking to make something like a dense fruit filled aspic/fruit terrine? If that is the case, you can cook down fruit with water or reduce fruit juice, cool, add gelatin and pour into your mold over your fresh fruit, cool until firm and serve. Note that the color of your fruit juice will add that color to your "cake". A springform pan may not be the easiest option, gelatins are usually made in a mold, but I'm no expert here.