Beat the eggs in a medium bowl, add the milk, the salt and vanilla extract and whisk until fully combined.
Cut the brioche Hot Dog Rolls in half, dip both sides into the egg and milk mixture.
Heat a large pan on medium heat and add one tablespoon of butter. Cook on both sides until golden brown.
In a separate pan, add the berries along with two tablespoons of sugar and a tablespoon of water and cook until the sauce thickens.
Serve the French toast with the berry sauce and a generous serving of mascarpone cheese. Drizzle with maple syrup and enjoy!