For the bubble and squeak cake: Mix the mashed potato with the onions, sprouts, garlic, cayenne pepper, and salt, then divide into 4 equal amounts. Shape into round cakes then leave them to set in the fridge for 20 minutes.
Pre-heat the grill to maximum. Cook the bacon and tomatoes on the grill then set them aside.
Remove the cakes from the fridge and brush both sides with a little olive oil. Place on the grill and cook for 6-8 minutes.
In the meantime, poach your eggs in gently boiling water for 3-4 minutes, or until your egg white is set.
To serve: place some wilted spinach on each serving plate and put a bubble and squeak cake on top. Top with the bacon and egg and serve with the tomatoes.