In a saucepan, combine the blackberries, balsamic vinegar, sugar, lemon juice, and a pinch of kosher salt. Bring to a boil over medium high heat then turn down the heat to allow the berries to simmer. Crush the berries with a wooden spoon.

Simmer the blackberries for 7 to 10 minutes until it reduces into a thick jam. Transfer the jam to a small bowl and set aside to cool.

Slice the brie cheese into ½ inch thick slices. Heat a skillet on medium heat.

Spread butter on one side of four slices of bread. Place butter side down in the pan. Top the bread with the brie slices and let it fry until the brie softens and the bread is golden brown. Sprinkle the cheese with chopped thyme.

Spread a thick layer of blackberry jam on the remaining bread slices and place jam side down over the brie cheese. Butter the top side of the bread and carefully flip the sandwich.

Continue to fry until the bottom piece of bread is golden brown and the brie is melted.

Transfer to a cutting board and let cool for a couple of minutes before cutting in half.