01 - In a small mixing bowl, beat the softened cream cheese, granulated sugar, and vanilla extract with a hand mixer until completely smooth and creamy. Gently fold in the fresh blueberries, taking care not to crush them.
02 - Lay out all 8 slices of brioche on a clean work surface. Divide the cheesecake filling evenly among 4 slices, spreading it in a generous, even layer. Place the remaining 4 slices on top to form 4 stuffed sandwiches, pressing gently to seal.
03 - In a shallow dish or pie plate, whisk together the eggs, whole milk, ground cinnamon, and kosher salt until fully combined and smooth.
04 - Dip each stuffed sandwich into the egg custard, allowing it to soak for 10 to 15 seconds per side. Ensure both sides are evenly coated, letting any excess drip off before transferring to a plate.
05 - Melt the butter in a large nonstick skillet or on a griddle over medium heat. Working in batches if necessary, cook each sandwich for 3 to 4 minutes per side until deeply golden brown and the filling is warmed through.
06 - Transfer the cooked French toast to serving plates. Dust generously with powdered sugar and finish with additional fresh blueberries, a drizzle of warm maple syrup, or a dollop of whipped cream as desired.