In a bowl whisk together crème fraiche, maple syrup and cinnamon. Chill until needed.
Heat a griddle pan over a medium-high heat until nice and hot. Brush the plums on the cut side with oil and place on the griddle. Cook for 3-4 minutes without moving until chargrill marks have appeared and the plums have softened slightly. Remove to a plate, cover with foil and set aside.
Meanwhile, in a large shallow dish, whisk the eggs with the cream. Add the vanilla, orange zest, cinnamon and sugar and whisk again until well combined (adding a drizzle of maple syrup if you like things sweet).
Melt a knob of butter in a large frying pan over a medium heat. Dip each slice of brioche into the egg mixture, letting it soak up the liquid for a few seconds before turning over to coat the other side. Once the butter is foaming, add the soaked brioche to the pan one or two at a time and cook for 2–3 minutes on each side until golden brown and crisp. Transfer to a wire rack in a just warm oven while you cook the remaining slices, adding a little more butter to the pan if needed.
Serve the French toast with the griddled plums and a dollop of cinnamon cream, drizzled with a little maple syrup. Garnish with toasted pistachio.
