Preheat the oven to 350°F (175°C). In a mixing bowl, combine flour and sugar. Add softened butter and mix until crumbly. Stir in the egg until the dough forms.

Press the dough into the bottom of a greased baking dish. Bake for 15 minutes or until lightly golden.

In a saucepan, combine blueberries, sugar, lemon zest, lemon juice, cornstarch, and salt. Cook over medium heat until the mixture starts to thicken and bubble, about 10 minutes.

Pour the blueberry mixture over the baked crust and spread evenly.

Return to the oven and bake for an additional 15 minutes. Allow to cool before serving.

Serve chilled or at room temperature, optionally garnished with whipped cream.