In a bowl, add blueberries and 1 tablespoon maple syrup and mix together.

In a separate bowl, add remaining 1 tablespoon maple syrup and cream cheese and mix together till smooth.

Spread cream cheese mixture on each of the challah slices. Place some (approximately 2 tablespoons, being careful not to overstuff) blueberries on two of the slices and top with the remaining two slices. Press firmly to make a sandwich.

In a separate bowl, add milk, egg, and salt and whisk together.

In a large skillet over medium heat, add 1 tablespoon butter.

Place one challah sandwich into the bowl with the milk mixture, fully coating it, then place in the skillet. Repeat with second sandwich.

Cook 3 to 4 minutes till golden brown. Flip over and cook 3 to 4 minutes on the other side.

Serve with dollop of plain Greek yogurt and remaining blueberries.