In a medium saucepan over medium-high heat, combine fresh blueberries, white sugar, lemon juice, and lemon thyme. Bring the mixture to a gentle boil, stirring occasionally.

Once bubbling, reduce the heat to low and let it simmer for about 10 minutes until thickened and syrupy. Remove from heat and allow the compote to cool.

Spread a generous layer of the cooled blueberry compote on four slices of your chosen bread. Sprinkle shredded white cheddar and mozzarella cheese over the compote, ensuring an even distribution.

Top each with another slice of bread to create sandwiches.

Heat a cast iron skillet over medium heat and add 1-2 tablespoons of butter. Allow it to melt and coat the bottom of the pan evenly.

Once the butter is bubbling, add your assembled sandwiches, making sure they're nicely coated with butter.

Grill for 2-3 minutes, or until the bottom is golden brown. Carefully cover the skillet with a lid to help melt the cheese.

Flip the sandwiches and grill the other side for an additional 2-3 minutes until crispy and the cheese is gooey.

Remove the sandwiches from the skillet and cut each sandwich in half for a delightful presentation. Optional: sprinkle with flaky sea salt and fresh lemon thyme leaves.