Preheat oven to 350 degrees F.

Grease an 8" square baking dish. Spread the blueberries in the bottom of the prepared baking pan.

In a small saucepan over medium heat, combine the sugar, cornstarch, water and 2-3 tablespoons lemon juice; cook and stir until thick and clear, then add in 1/2 teaspoon vanilla.

Pour over, then gently stir in the cooked mixture with the blueberries.

In a medium bowl, combine the flour with oats, brown sugar and cinnamon.

Add in the melted butter; mix until crumbly (you may need to use your hands).

Sprinkle over the top of blueberries.

Bake for 30-35 minutes or until the blueberry juice bubbles and the topping is brown. Remove from oven and let cool slightly (approximately 10-15 minutes).

Just before serving, pour cold heavy whipping cream into a bowl and beat at high speed until soft peaks form. Stir in sugar and vanilla and continue beating until stiff peaks form.

Serve warm with fresh whipped cream on the side.