Nutrition per serving may change if servings are adjusted.
⅓ cup rolled oats
⅓ cup all-purpose flour
⅓ cup packed light brown sugar
1 tablespoon canola oil
1 tablespoon apple or cranberry juice
¼ teaspoon ground cinnamon
1½ cups all-purpose flour
½ cup granulated sugar
1 tablespoon baking powder
½ teaspoon salt
1 large egg
1 cup buttermilk
3 tablespoons canola oil
1 tablespoon freshly grated lemon zest
1 teaspoon vanilla extract
1 cup frozen raspberries, thawed
1 cup frozen blackberries, thawed
To prepare topping: Position oven rack in lower third of oven; preheat to 375°F. Stir together oats, ⅓ cup flour, brown sugar, 1 tablespoon oil, apple (or cranberry) juice and cinnamon in a small bowl; work the mixture together with your fingers until it is evenly moistened.
To make cake: Coat a 9-inch springform pan with cooking spray. Stir together 1½ cups flour, granulated sugar, baking powder and salt in a large bowl. Whisk together egg, buttermilk, oil, lemon zest and vanilla in another bowl.
Add the egg mixture to the flour mixture and stir with a rubber spatula just until blended. Spread the batter evenly in the prepared pan. Scatter the berries over the batter, then sprinkle with the topping.
Bake until the top feels firm when lightly pressed in the center, 40 to 45 minutes. Remove the pan sides; serve warm or at room temperature.