Fry onions and garlic over medium heat until soft.
Add oregano, chilli flakes, 'nduja, passata, borlotti beans, red wine vinegar and stock to the pot. Stir to combine. Bring to a boil, then cover and turn to a simmer for 15 minutes.
Mustard Parmesan Breadcrumbs: Chop bread into fine cubes. Transfer to a bowl. Add mustard, salt, and grated parmesan. Stir to combine. Next, add olive oil and combine again. Heat a non-stick frying pan and toss breadcrumbs around until crispy. Remove and set aside.
Remove beans from the heat and stir through the grated parmesan and olive oil. Season with salt and pepper, then cover to keep warm.
Using the same pan, sautee spinach in a hot frying pan with a little oil and salt until just wilted. Remove from pan, set aside and keep warm.
Wipe the frying pan clean, heat the oil until very hot and break in the eggs. They should bubble furiously so that the edges are nice and crispy. Season with salt.
Plate up: Add a large scoop of beans to the plate. Top with a crispy fried egg and a side of spinach. Garnish with croutons.