In a shallow dish, whisk together 3 large eggs, 1/2 cup whole milk, 1/4 cup heavy cream, 2 tablespoons granulated sugar, 1 teaspoon vanilla extract, 1/2 teaspoon ground cinnamon, and a pinch of salt until smooth.
Heat 1 tablespoon unsalted butter in a large non-stick skillet over medium heat until melted and shimmering.
Dip one slice of brioche bread into the custard mixture, soaking about 15–20 seconds per side without letting it fall apart.
Place 2–3 soaked slices into the hot skillet without overcrowding and cook 3–4 minutes per side, or until golden brown and cooked through.
Add more butter as needed and repeat with remaining brioche slices.
Serve immediately topped with warm maple syrup, fresh berries, and a dusting of powdered sugar.