In a medium saucepan over medium heat, combine the blueberries, granulated sugar, lemon juice, and cornstarch. Cook until the mixture becomes thick and bubbly, about 8-10 minutes. Stir occasionally to prevent sticking. Set aside to cool.

Preheat your oven to 450°F (230°C) and prepare an 8x8-inch baking dish by greasing it lightly.

In a large bowl, whisk together the flour, sugar, baking powder, lemon zest, and baking soda. Incorporate the frozen grated butter until the mixture resembles coarse crumbs—aim for a mix that resembles little pebbles.

Pour in the buttermilk and stir gently with a spatula until just combined. Avoid overmixing; a few lumps are okay.

On a floured surface, gently press the dough into a flat square about 1-inch thick. Fold it over three times, turning it 90 degrees each fold, then cut out biscuits with a round cutter or a sharp knife for squares.

Place the biscuits in the prepared dish. Brush the tops lightly with buttermilk, then bake for 14-16 minutes or until golden brown. Allow them to cool slightly before serving.

In a medium bowl, beat the heavy cream and confectioners' sugar together until stiff peaks form. This should only take a few minutes, so keep an eye on it!

Slice a biscuit in half, layer with the blueberry topping and whipped cream, and repeat with the remaining biscuits. Serve immediately for the best experience!