Preheat the oven to 180°C (350°F). This recipe is for a baking dish of approximately 22 cm × 14 cm × 5 cm (8.5” × 5.5” × 2”).
Rinse and drain the blueberries. Place them in a mixing bowl. Add sugar, lemon juice, and cornstarch. Mix well.
Melt the butter using a microwave or over a double boiler. Roughly chop the sliced almonds.
In a mixing bowl, combine flour, brown sugar, chopped almonds, salt, vanilla extract, and melted butter. Mix with a spatula until just combined. Squeeze and break apart the mixture a few times by hand to form uneven crumble clusters.
Pour all the blueberries into the baking dish, then evenly sprinkle the crumble topping over the surface. Bake in the preheated oven for 50 minutes, or until the crumble is golden brown and the blueberry juice is bubbling at the edges.
Let cool at room temperature for 1 hour before serving.
You can scale the ingredient quantities proportionally depending on the size of your baking dish. Adjust baking time accordingly.
A small amount of sugar and lemon juice enhances the sweet-tart flavor of the blueberries and boosts the fruity aroma. Cornstarch thickens the juices during baking, working with the natural pectin in the blueberries to create a spoonable filling.
Brown sugar can be substituted with granulated sugar, though brown sugar adds a caramel-like depth. Sliced almonds can also be replaced with almond flour.
If the baking dish is very full, juices may bubble over during baking. Placing a tray underneath the dish can help prevent messes in the oven.
Cooling is not only to avoid burning your mouth—pectin helps thicken the blueberry juice as it cools, and the crumble topping becomes crispier.
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