Pre-heat the oven at 180 degrees. In a large bowl, take 3 cups of fresh blueberries. You can use frozen too.
Then, add lemon zest, lemon juice, sugar, cinnamon powder, corn flour.
Toss everything and layer it into baking dish.
In another bowl, combine oats, sugar, cinnamon powder, a generous pinch of clove powder, almond flour and sliced almonds. Give it a mix.
Now, add 4 tablespoons of softened butter and mix using a fork. The mixture should be like a crumble.
Sprinkle the oats crumb mixture over blueberries.
Bake it for 40 minutes until top is golden brown crisp and fruit is bubbly. Let to cool until just warm.
Scoop out in serving bowl, top to with your favorite topping and serve warm.