All the time you're working with filo pastry, make sure that it remains covered with a damp cloth because it dries up easily and breaks.
Paint a sheet of filo pastry with little butter in an even manner. Place it in the bundt pan to one side, with the butter facing the pan. Press carefully into it so it goes into the shape of the pan.
Repeat this with two-thirds of the sheets, covering every part of the pan more with about 3 layers. If there's excess dough on the sides then that's perfect, we will fold them inwards later and helps to close it up.
Pour the filling into the dough and level it with a spatula or spoon.
Fold the excess dough inwards and place the rest of the filo sheets with butter on top for the base.
Bake the cake at 180°C/350°C for 45 minutes.
Turn over onto a baking tray (if you don't have a pizza peel for later, place a bit of baking paper first).
Return to the over for an extra 5-10 more minutes, just to get it golden on top.
Let it cool for 15 minutes and serve.