Preheat your oven to 350°F (175°C).
Wash and dry the blueberries, then place them in a baking dish.
Add lemon juice and a tablespoon of brown sugar to the blueberries, mixing gently.
In a separate bowl, combine oats, flour, brown sugar, cinnamon, and salt.
Pour melted butter into the dry mixture, stirring until crumbly.
Sprinkle the oat mixture evenly over the blueberries.
Bake for 25-30 minutes or until the topping is golden brown.
Remove from the oven and let it cool for 10 minutes.
Serve warm with a scoop of vanilla ice cream or whipped cream.
Enjoy your delicious blueberry crumble!