For the Filling:
2 pints fresh blueberries
1/4 cup granulated sugar
1/4 cup soft brown sugar
Pinch of salt
Zest of 1 small lemon, plus 2 Tablespoons juice
2 Tablespoons corn starch
For the Topping:
1-1/2 cups all-purpose flour
1-1/2 teaspoons baking powder
1/4 teaspoon fine salt
1/4 teaspoon ground cinnamon
6 tablespoons cold butter, cut into small pieces
1/4 cup granulated sugar, plus 1 tablespoon
3/4 cup heavy cream, plus 2 Tablespoons
1 large egg yolk
1/2 teaspoon vanilla extract
Preheat over to 375°F. In a medium bowl, combine all the ingredients for the filling and mix well. Transfer to a 1-1/2 quart baking dish.
Make the topping: In a large bowl, stir together the all-purpose flour, baking soda, salt and cinnamon. Add the butter, and using your fingers or a couple of knives, cut or rub the butter into the flour mixture until it resembles coarse bread crumbs. Stir in the sugar. Whisk together 3/4 cup of the cream, egg yolk and vanilla extract in a bowl or jug. Pour the cream mixture into the cobbler crumbs and mix lightly to combine until a soft dough forms.
Drop spoonfuls of the cobbler topping over the blueberry filling, leaving a few gaps between the mounds. Brush the dough with the remaining heavy cream and sprinkle over the remaining sugar. Bake for 30 to 40 minutes, until the filling is bubbling and the cobbler topping is golden brown. If it is browning too quickly, cover with foil. Leave to cool for at least 20 minutes, and serve warm or at room temperature, with vanilla ice cream or whipped cream.