This simple dessert (a cross between a cobbler and a buckle) comes together in minutes. If you don't have buttermilk, add 2 tsp lemon juice to 3/4 c sweet milk about 15 minutes ahead of time. In that case, add some lemon zest to the batter, too.
Preheat oven to 350°F Put butter in a 9" round cake pan and place in oven until butter is melted.
In a bowl, whisk together flour, sugar, soda and salt until combined. Add buttermilk and whisk until smooth.
Pour batter into cake pan. Scatter berries evenly over the batter.
Stir sugar and cinnamon together. Sprinkle over the berries. Bake in preheated oven 50-60 minutes, until cake is brown and berries have burst. Serve warm or at room temperature, with vanilla ice cream or whipped cream.