Berry Pudding Cake (The Best)

Ingredients

• • 1 cup (250 ml) sugar
  • 2 tsp (10 ml) cornstarch
  • 2 cups (500 ml) frozen raspberries
  • 2 cups (500 ml) frozen blueberries
  • 3/4 cup (180 ml) unbleached all-purpose flour
  • 1 tsp (5 ml) baking powder
  • 1 pinch salt
  • 6 tbsp (90 ml) unsalted butter, softened
  • 1 egg
  • 1/2 tsp (2.5 ml) vanilla extract
  • 1/4 cup (60 ml) milk