I made my favorite butter biscuit, and I'll give you a link to the recipe below.
You can use Savoyardi cookies, which are slightly steeped in compote or a traditional base of cookie crumbs. But the cheesecake is so tender that the biscuit is very much in the theme here. I didn't soak the biscuit in anything.
Place the sponge cake in a form 15 cm in diameter, pre-covering the bottom with baking paper, and the sides with film.