Preheat oven to 350 F. Slice brioche into ½" thick slices.
Spray a standard-sized loaf pan with baking spray or line the bottom and sides with parchment paper.
In a large bowl, whisk together milk, cream, eggs, vanilla extract, almond extract, cinnamon, vanilla bean powder, and kosher salt.
Dip brioche into egg mixture, thoroughly coating each side, then place standing up in the loaf pan. Repeat until all bread is coated. You could also lay the bread flat in a baking dish and pour the egg mixture on top. Either way, don't leave the bread soaking for more than a minute or two. Brioche is extremely light and delicate, and additional time will cause it to fall apart.
Bake for 30 minutes, then top with slivered almonds. Return to oven and cook for 5 minutes more, or until lightly golden brown on top and eggs has formed a thin crust on the bread. Cool for 10-15 minutes, then serve with powdered sugar and maple syrup.
*If you can't find vanilla bean powder, simply omit and increase vanilla extract to 1 Tbsp.