In a small bowl, mash half of the blackberries with a fork to create a spreadable consistency. Leave the rest whole for adding to the sandwich later.
Heat a non-stick skillet over medium heat and add the butter, allowing it to melt and coat the bottom of the pan.
Take two slices of bread and spread a layer of the blackberry mash on one side of each slice.
Layer 2 slices of cheese on top of the blackberry spread on each slice of bread.
Place 2 slices of crispy bacon on top of the cheese on one of the slices.
Scatter some whole blackberries over the bacon, then close the sandwich with the other slice of bread, blackberry side down.
Place the sandwich in the skillet once the butter is hot. Cook for about 3-4 minutes or until the bottom is golden brown, then carefully flip using a spatula.
Cook the other side for an additional 3-4 minutes, pressing gently with the spatula to ensure even cooking and melting.
Once both sides are golden and the cheese is melted, remove the sandwich from the skillet and repeat with the remaining ingredients to make more sandwiches.
Allow the sandwiches to cool for a minute, then slice in half and serve warm. Enjoy!