Preheat oven to 350°F. In a large bowl, toss bread cubes with croissant cubes and currants; set aside. In a saucepan, combine milk and butter over medium heat until butter is melted, about 5 to 6 minutes. Pour milk mixture over the bread mixture and set aside to let sit for 15 minutes to absorb the liquid. In a medium bowl, mix brown sugar, eggs, nutmeg, cinnamon and vanilla, then pour over bead and milk mixture and stir to combine. Spoon contents of bowl into a lightly greased 9-inch baking dish or casserole pan and bake for 45 minutes, or until golden brown and set in the center.

Meanwhile, for the maple vanilla sauce, combine sugar with maple syrup, cream and butter in a saucepan over medium heat. Bring to a boil, stirring often. Boil for 5 minutes, stirring occasionally. Remove from heat and stir in vanilla. Set aside to let cool and thicken, then serve spooned over warm bread pudding.