Preheat your oven to 180°C. Line your tray with baking paper. Make sure the paper covers all sides. This helps the cake come out easily after baking.

In a large bowl, mix butter and sugar. Beat until light and fluffy. This step adds air to the batter. It helps the cake become soft and tender.

Add eggs one at a time. Mix well after each egg. This keeps the batter smooth. If it looks curdled, do not worry. It will fix later.

In another bowl, mix flour and baking powder. Slowly add this to the wet mixture. Stir gently to keep the batter soft and light.

Pour in milk and vanilla extract. Mix until smooth. The batter should be soft but not too runny. This gives the cake a rich flavor.

Take your blueberries and coat them with a little flour. This stops them from sinking. It helps them spread evenly in the cake.

Gently fold the blueberries into the batter. Do not overmix. You want to keep the berries whole and juicy.

Pour the batter into your lined tray. Spread it evenly using a spatula. Make sure the surface is smooth before baking.

Place the tray in the oven. Bake for 30 minutes. The top should turn golden. Insert a toothpick to check. It should come out clean.

Remove from oven and let it cool. Place on a rack. Once cool, dust with icing sugar. Cut into squares and serve fresh.