Steam the cauliflower florets over boiling water for about 5 minutes, or until just tender. Drain well.
Meanwhile, finely chop the spring onions and herbs, drain the beans and mince the garlic.
Place the cauliflower in a large bowl with the cannellini beans. Mash with a fork or pulse briefly with a hand blender until you have a coarse mixture.
Add the garlic, egg (if using), chilli flakes, spring onions, herbs and a little salt and pepper. Mix well.
If the mixture feels too wet to shape, stir in enough chickpea flour to form a soft but workable mixture.
Leave the mixture to rest for 5–10 minutes.
Divide into equal portions and shape into burger patties.
Heat a little oil in a non-stick frying pan over a medium heat.
Lightly dust the patties with chickpea flour, then fry for 3–5 minutes on each side until golden and heated through.
Lightly toast the burger buns, if using.
Serve the burgers in toasted buns or lentil wraps with your favourite toppings and condiments, or enjoy them with a fresh green salad.