In a bowl, mix cream cheese, caster sugar, and vanilla extract until smooth. Gently fold in blueberries.
Slice brioche into thick slices and cut a deep pocket in each slice, or prepare sandwich-style slices.
Fill each slice with 1–2 tablespoons of cheesecake mixture and gently press edges to seal.
Whisk egg, milk, cream, and cinnamon in a shallow dish to make the custard.
Dip stuffed brioche into custard, coating both sides.
Heat butter in a skillet over medium heat and cook French toast for 3–4 minutes per side until golden. This Blueberry Cheesecake Stuffed French Toast should be crisp outside and creamy inside.
Serve warm with icing sugar, blueberries, and maple syrup.