STEP 1:

Preheat oven to 180°c. 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 1/4 cup sugar. Arrange pineapple rings in pan.

STEP 2:

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

STEP 3:

In a large bowl, whisk together buttermilk, eggs, vanilla extract, oil, and remaining 3/4 cup of sugar. Add flour mixture; mix until combined. Pour batter over the pineapple. Tap pan firmly on counter to settle batter, then smooth top.

STEP 4:

Bake until a toothpick inserted in the centre of the cake comes out clean, this will take 50 to 60 minutes.

STEP 5:

Cool for 20 minutes in pan; invert onto a serving platter (peel off and discard paper).