If you can, use younger fig leaves, which sounds a little esoteric (I know...) but the leaves seem to lose their flavor the longer they're on the tree. Fig leaves contain an enzyme (ficin) that can cause the milk and cream mixture to curdle slightly after they're infused. If that happens, simply whisk the mixture after removing the fig leaves, and it should come back together. I normally don't use an instant-read thermometer for making custards, but you don't want to overcook this one, so I used a thermometer and stop cooking the custard when it just started to thicken; the temperature was 160ºF. (If you do overcook the custard and it starts to separate, you can blend the warm custard with an immersion blender, or in a standard blender but note that you shouldn't fill a standard blender more than one-third to one-half full when blending a warm or hot liquid as the top of the blender can come off. I advise also covering the lid with a kitchen towel, as an extra precaution.)