In a large bowl, whisk the eggs vigorously, then add the single cream, vanilla and sugar, and whisk again.
When you’re ready to cook, heat the oven to its lowest setting, pop a baking tray inside and pour the cream mixture into a shallow dish or tub that will allow space for the brioche to lay flat. Heat a griddle or a frying pan to a medium heat, and melt the butter and the oil together.
Place the brioche slices in the cream mixture for 1 min, then turn each slice and gently press all over, allowing them to soak up the liquid for another 1 min or so until fully soaked.
Remove the brioche from the mixture and place onto the hot griddle or pan (you may need to do this in batches). Cook for a few mins on either side until the inside is tender and moist (but not wet). To check this, make a small cut in the middle with a knife – the inside should be like cooked bread pudding. Keep warm in the oven while you cook the remaining slices.
In the meantime, fry the bacon in a pan for 5 mins until crispy. Serve the French toast topped with bacon, bananas and a drizzle of maple syrup.