Set your oven to 350°F (175°C) and grease a round or square cake pan.
In a bowl, mix 1 cup sugar, 1/2 cup butter, 2 eggs, 1 1/2 cups flour, 1 1/2 tsp baking powder, 1/2 cup milk, and 1 tsp vanilla extract until smooth.
Gently fold in 1–2 cups of fresh or frozen mixed berries (blueberries, raspberries, strawberries, etc.).
Pour the batter into the prepared pan and spread evenly.
Sprinkle a few extra berries on top and dust with 1 tablespoon of sugar for a sweet crust.
Bake for 35–40 minutes or until a toothpick inserted in the center comes out clean.
Let it cool slightly, then serve warm or chilled—great with whipped cream or vanilla ice cream!