Pain perdu was probably invented as a thrifty way to make dessert from pieces of stale bread, but it feels luxurious enough for royalty -- as most of you already know from eating it for brunch, under the name of French toast. This one can be breakfast or a dessert. We serve it at Tru as part of our dessert collection. In France, pain perdu (which means "lost bread") is only served as a dessert. We like to make it on the grill, which gives it a lovely campfire taste, but you could certainly brown it in butter over high heat if you prefer. I switched to grilling my pain perdu when invited to participate in a grilling event -- always a challenge for a pastry chef. I was sure there must be more to grilled desserts than the usual fruit kebabs!
In a medium bowl, whisk the eggs. Whisk in the sugar, salt, and vanilla. Gradually whisk in the half-and-half and the buttermilk. Pour the mixture into a shallow baking dish. Working in batches, if necessary, place the bread in the dish and let soak, then turn and soak on the other side.
Cook the soaked bread on a grill or buttered griddle until golden brown, then turn and repeat on the other side.
Meanwhile, prepare the grapefruit sections.
In a saute pan, add the maple syrup and bring to a boil. Place the grapefruit sections in the hot syrup and cook on 1 side for 30 seconds, then flip them over to cook and warm through on the other side. Pour the grapefruit and syrup over the French toast then top with dollops of mascarpone.