Sift the flour into a large bowl. In a second bowl, whisk together the eggs and the milk until combined, then stir in 300ml of water.
Mix the liquid into the flour until you have a smooth batter (be careful not to over-mix it) and stir in a pinch of sea salt.
Melt the butter in a 26cm frying pan over a medium-low heat, then pour it into your crêpe batter and whisk to combine.
Using the same pan, ladle in just enough mixture to coat the base. Cook for 1 minute, until golden, then flip it and cook for 1 minute on the other side.
Transfer the crêpe to a plate, then repeat until you’ve used up all of the mixture, brushing the pan with a little extra butter if needs be – it should make around 30 crêpes in total. Set them aside to cool.
Line a board with greaseproof paper. In the frying pan, fry 4 slices of pancetta over a medium heat for about 2 minutes, or until crisp, turning halfway.
Drizzle on 1 tablespoon of maple syrup and fry for a few more minutes, until caramelised – transfer to the lined board. Repeat with the rest of the pancetta.
Save a couple of rashers to serve, then roughly chop the rest and set aside until you’re ready to use them.
Toast the pecans in a dry frying pan over a medium heat, and set aside.
Line a baking tray with greaseproof paper and scatter over the pecans. Again using the same frying pan, melt the sugar over a medium-low heat for 10 minutes, or until it’s a golden caramel – don’t stir, just swirl the pan.
Quickly pour the caramel over the pecans to coat, then set aside to harden.
Once set, break the pecan praline into large pieces. Reserve one-third for the topping and smash the rest into coarse granules using a pestle and mortar. Set aside while you make the buttercream.
Cream the butter and icing sugar in the bowl of a free-standing mixer for 5 minutes, until pale and smooth. Beat in the maple syrup and set aside.
Now assemble your cake. Spread each crêpe with a thin layer of buttercream and sprinkle the praline or chopped pancetta over every other one. Pile them up on a serving board or cake stand.
Finish with a layer of buttercream and the reserved pecans and pancetta. Pop the cake in the fridge for 30 minutes to set, then serve.