Slice the sweet potato into 1cm slices, chop the bacon into strips, peel and slice onions.
Cook the bacon in a frying pan over a medium heat until browned slightly, remove and keep to one side.
Add the mince and onions to the pan and stir-fry. Add the smoked paprika, cayenne, chilli, oregano, mixed herbs and tomato puree. Continue to fry for a further 10 minutes, stirring occasionally until the meat is browned and the onions have softened.
Whilst the meat is cooking in the pan prepare the eggs. Beat them in a large bowl, add a pinch of salt and pepper and set to one side.
Grease the base and sides of a casserole dish (around 9×13 inch dish, remember the egg will rise a bit). Layer the dish several times over in the following order: sweet potato scattered | bacon scattered | beef mince onion and spices.
Repeat this until you have no ingredients left and then pour the egg mix over the top. Move the dish side-to-side to ensure the egg fills all the gaps. Place it the dish in the oven and cook for 1 hour.