Cook blueberries: In a saucepan over medium heat, combine 1 cup of fresh blueberries, 1.5 tablespoon sugar or honey, and 1 teaspoon lemon juice. Stir until the mixture thickens and the blueberries start to burst, about 5 minutes.

Butter bread: Take 4 slices of your chosen bread (sourdough or brioche) and spread softened butter generously on one side of each slice.

Layer ingredients: On the unbuttered side, place 2 slices of your preferred melting cheese, spoon a generous portion of the blueberry filling, and add another slice of cheese on top.

Cook the sandwich: Heat a skillet over medium-low heat. Carefully place the assembled sandwich in the skillet, cooking until the bread is golden brown and the cheese has begun to melt, about 3-4 minutes.

Flip gently: With a spatula, carefully flip the sandwich to cook the other side, ensuring it turns equally golden brown and the cheese is melty, approximately another 3-4 minutes.

Rest and slice: Once cooked, let the sandwich rest for a minute to allow the cheese to set slightly. Then, slice it in half and get ready to enjoy!