Preheat the oven to 180°C (fan oven). This is 200°C for conventional ovens (or 400°F / gas mark 6).

Combine the almond flour, extra-fine almond flour, salt and finely grated Parmesan cheese in a bowl. Pour in the melted butter and mix well to combine.

The mixture will resemble course breadcrumbs. Tip the mixture into a large well-greased pie dish (I always line the base with parchment too) and use a spatula to spread it out as evenly as you can, moving a lot of the mixture to the sides.

Use clean hands to compress the mixture down into an even layer at the bottom, as well as up the sides of the dish until you have a smooth, compact later all over.

Bake in the oven for 10 minutes, then remove and set aside. Do not turn the oven off.

In the meantime, whisk the eggs very well in a large bowl, adding in the mustard powder, baking powder and a little salt. Stir in the grated Gruyere, Gouda and Cheddar cheese. Set aside.

Snap off the hard, woody ends of the asparagus and (unlike what I have done in the pictures) I advise you cut them into smaller pieces - it makes for easier slicing later.

Place the asparagus into the tart case and pour over the creamy egg cheese mixture. Try and ensure that the cheese is evenly distributed.

Place the tart tin onto a baking tray (in case any mixture bubbles over) and bake in the oven for 15 minutes.

After 15 minutes, rotate the tray (my own personal habit, its not necessary) and reduce the oven to 140°C (fan oven). This is 160°C for conventional ovens (or 325°F / gas mark 3). Cook on this lower heat for another 18-20 minutes. (The reduced temperature will ensure the mixture cooks through sufficiently without burning the eggs or crust.)

The mixture should not wobble in the centre and be fairly firm. Remove and allow to cool for at least an hour before slicing and serving.