Preheat oven to 350 degrees F. Line a baking sheet with parchment.
To make the cinnamon crunch: In a small skillet, set over medium heat, add the bread crumbs, sugar and cinnamon. Stirring frequently, toast until medium golden brown. (The stirring is a must because the sugar will begin to caramelize which is great, you just don't want to get it too too brown or else it will get too sticky!) Transfer to a small bowl. Rinse out the skillet.
To make the brown sugar syrup: To the washed out skillet, add the brown sugar, water and cinnamon. Heat until the sugar dissolves and the mixture is at a slight simmer. Turn off the heat and allow to steep for 10 minutes.
To make the cinnamon smear: add the butter, all-purpose flour, egg, cinnamon, vanilla and salt to a medium bowl or bowl of a stand-up mixer (with a paddle attachment). Mix until ingredients are thoroughly combined and mixture is fluffy.
Lay the brioche slices side by side on the lined baking sheet. Brush both sides of the brioche with the syrup. Smear a tablespoon of the cinnamon smear on each piece of the toast. Transfer to the oven to bake for 15 minutes. At the 15 minute mark, remove from the oven and sprinkle on the cinnamon crunch and a few pearl sugar granulates, if using, return to the oven to bake for an additional 2 to 3 minutes. Divide amongst plates and serve.