Preheat oven to 170 to 180℃.
Mix softened Butter and Sugar until smooth. Add Egg Yolk and mix until creamy. Add Plain Flour and mix as you cut the butter mixture into flour. After mixing, it might look too DRY, but do not add Water. Use your hands to bring the mixture together.
Spread the dough in a pie dish, bit by bit, press using your fingers and make it even thickness. *Alternatively you can roll out the dough to 3-4mm thick, and place in the pie dish.
Spread fresh or thawed Blueberries in the pie dish. If thawed Blueberries are still cold, it is OK.
Combine Sour Cream, Caster Sugar, Egg and Flour in a bowl, then WARM in the microwave. Do not cook the mixture, you just need to warm it at low power for a few minutes. Pour the mixture over the Blueberries.
Bake for 40 minutes or until cooked through and golden. Enjoy warm or cold. I like it cold.
