Preheat oven to 400F. Grease a 9 x 13-inch (23 x 33cm) baking pan & line base & sides with parchment paper.
Whisk flour & sugar together in a medium bowl.
In a medium bow, whisk together the buttermilk, the half the melted butter, eggs & vanilla until well combined. Add to the flour mixture. Whisk until just combined.
Brush the parchment paper with a little extra melted butter. Scrape the batter into the pan. Scatter with the fruit, leaving about 1/2 cup for serving. Drizzle the batter with the remaining butter. Bake for 20 minutes until set. Then broil for 2 minutes, 6 inches away from heat source, until golden. Let stand for 5 minutes before cutting into 6 servings. Serve dusted with icing sugar, maple syrup, whipped cream & extra berries.