3 tablespoons unsalted butter, plus more for greasing the pan
3/4 cup (75g) oat flour
1 cup (160g) medium-ground cornmeal
1 teaspoon baking powder
1/2 teaspoon baking soda
2 large eggs, beaten
1/4 cup (45g) natural cane sugar
1 teaspoon kosher salt
1 1/2 cups (360 ml) whole milk
1/2 cup (120 ml) buttermilk
1 1/2 tablespoons white vinegar
2 teaspoons grated lemon zest
2 teaspoons vanilla extract
1 1/4 cups (300g) fresh or frozen huckleberries or blueberries
3/4 cup (180ml) heavy cream
Grade B maple syrup, for serving