In a small saucepan, add the blueberries and water. Only add the water if you are using fresh berries. You don't need water if you are using frozen berries. Stir in the sugar or honey. Cook over medium heat until blueberries begin to pop and are juicy. Remove from heat and set aside.
Spread butter on one side of each slice of bread.
Evenly place slices of brie cheese on unbuttered side of two slices of the bread. Spread lemon curd evenly on the bread slices. Top with blueberries and addition slices of brie cheese. Top with remaining slice of buttered bread.
Heat a skillet over medium high heat. Place sandwich, butter side down, in pan. Cook for 2-3 minutes on each side or until lightly toasted and cheese melts. Remove from pan and cut sandwich in half, if desired. Serve immediately.
Note-I used store bought lemon curd from Trader Joe's. You can make your own though!