Light Pineapple Upside-Down Cake

1. Preheat oven to 350 degrees. Brush a 9-inch square baking pan with oil; line with a strip of parchment paper, leaving an overhang on two sides. Brush paper with oil. Sprinkle bottom of pan with ¼ cup sugar. Trim pineapple wedges to no more than 4 to 5 inches long; arrange in pan in groups of four, alternating direction.

2. In a medium bowl, whisk together flours, baking powder, baking soda, and salt; set aside.

3. In a large bowl, whisk together buttermilk, eggs, vanilla, oil, and remaining ¾ cup sugar. Add flour mixture; mix just until combined. Pour batter over pineapple. Tap pan firmly on counter to settle batter, then smooth top.

4. Bake until a toothpick inserted in center of cake comes out clean, 50 to 60 minutes. Cool 20 minutes in pan; invert onto a serving platter (peel off and discard paper).