Add the softened cream cheese through the feed tube, breaking
it into chunks as you add it. The goal is silky smooth, so stop the
processor and scrape a few times or break up large chunks that aren’t
processing.

If you have a tiny processor (like me at home), process the banana/sugar
with the cream cheese, then scrape the mix out into a bowl and whisk the
rest of the ingredients in by hand.

Weigh the egg and crème fraîche and finely grate the tonka bean on
top. Add this in one addition and process until the mixture forms a
smooth, homogenous mix. Hand whisk or strain any obstinate lumps
out at the end if needed. This mix is deliriously good – like the most
extra, extra banana smoothie. Transfer to a bowl and set aside. Clean
the food processor bowl.

When the crumb has cooled, whiz in a food processor to a coarse
damp sand consistency – a few small pea-sized almond pieces are
fine to remain, and will give lovely texture.

Don’t over-process or you’ll end up with a but tery cookie paste!

Lightly spray a 20 cm (8 in) round × 7.5 cm (3 in) deep cake tin with
cooking oil and line the base and side with baking paper. Set up a
high-sided roasting tin for the water bath and place a piece of paper
towel in the base to stop the cheesecake tin slipping.

If you choose a tin where the base is welded to the side (or a springform tin),
you will need to wrap the outside of the tin with a triple layer of extra-wide
foil so water won’t breach the tin. If you use a tin made from a single piece
of metal, you won’t need to do this – this is the type of tin that I prefer to use.

Fill the base of the tin with half the crumb – approximately 160 g
(5½ oz). Pack it down lightly – the weight and moisture of the
cheesecake mix will do the rest of the work, and you don’t want a
base you have to really crunch through when eating. Reserve the
remaining crumb for the top.

Pour the filling into the prepared cake tin, then place the cake tin in
the roasting tin. Gently scatter the reserved crumb evenly over the
top, being careful not to make any sudden movements that could
slosh the filling and crumb together. With an angel’s touch, smooth
out the crumb top with an offset spatula.

Mythbuster: there is no need to re-bake the crumb base before filling. The
base will hold together fine with the extra moisture from the filling.

Pour enough hot tap water into the roasting tin to just reach the first
joint on your index finger.