In a medium bowl, whisk together eggs, milk, heavy cream, sugar, vanilla extract, cinnamon, and salt until smooth.
Heat a nonstick skillet or griddle over medium heat and melt butter to coat the surface.
Soak each slice of brioche in the egg mixture for 15–20 seconds per side, then shake off excess.
Place slices in the skillet and cook 2–3 minutes per side until golden brown. Adjust heat as needed.
Rinse and pat dry fresh blueberries. Optionally, sauté in butter with sugar for 1–2 minutes.
Stack cooked brioche slices, top with blueberries, drizzle with syrup or honey, and add powdered sugar or whipped cream if desired.
Serve immediately warm with optional sides like coffee or fruit smoothies.