Preheat the oven to 375 degrees and grease a muffin tin or line with paper liners.
Whisk together brown sugar, melted butter, egg, milk, and vanilla until well combined.
Stir together flour, salt, baking powder, and cinnamon. Slowly add in flour mixture a little at a time and stir until all incorporated. Stir in the blueberries.
In a separate medium bowl, mix the melted butter with the sugar and flour until it is a chunky sand type consistency.
Spoon the mixture into the muffin tin, filling ¾ of the way up. Top with a bit of granola and then evenly divide the topping over top of the batter and bake for 20-25 minutes or until the tops bounce back in the middle.
Let cool for 10 minutes and then remove and let continue to cool on a wire rack or counter top.