Toss the potatoes with olive oil and salt and transfer to a baking sheet. Allow to bake until crisp and golden (approximately 30 minutes) then remove from the oven.
In the meantime, fry the onion and bacon until the bacon is crisp. Add the garlic and cook for another 20 seconds then remove from the heat.
Place the potatoes, bacon and onion mixture and half of the cheese into a casserole dish.
Whisk the eggs, milk, cream and seasoning together and pour over the potatoes and bacon. Top with the remaining cheese and place in the oven.
Allow to bake for 30-40 minutes until golden brown and cooked through. Remove from the oven, allow to rest for 5-10 minutes then slice and serve.