Prepare a slow cooker crock with nonstick cooking spray.

Slice the bread - set aside.

In a medium bowl, stir together the brown sugar, cinnamon, and melted butter until completely blended and sandy in appearance.

Sprinkle the bottom of the slow cooker with ¼ of the brown sugar mixture.

Place an even layer of the sliced bread on top. Cut pieces of bread if needed to fill the gaps.

Sprinkle ¼ of the remaining brown sugar mixture on top of the bread.

Top with ¼ of the blueberries.

Repeat the layers twice, finishing with a layer of blueberries.

In a large bowl, whisk together the eggs, milk, vanilla, and salt, beating until well blended.

Pour the egg mixture evenly and slowly over the bread, allowing it to soak into the bread.

Cover and refrigerate the casserole for at least 1 hour or up to overnight.

Place the slow cooker crock into the slow cooker and cook on low for 3 to 4 hours. Allow the slow cooker to rest for 15 minutes prior to serving.

Serve the French toast with whipped cream, confectioner’s sugar, syrup, and/or additional blueberries.