Preheat oven to 300 degrees F.
Combine flour, baking powder and salt. Whisk until well blended.
In mixer bowl, combine sugar and egg. Using paddle attachment, mix on low speed 30 seconds. Increase speed to medium. Beat until light and fluffy, 2 to 3 minutes. Add olive oil and yogurt. Beat until well combined, 2 to 3 minutes.
Reduce speed to low. Add flour mixture, beating until well blended. Stop mixer. Scrape bowl and paddle. Mix on medium speed 1 minute. Do not overmix.
In 8x8 pan coated with cooking spray, spread batter.
Bake until wooden pick inserted in center comes out clean, 25 to 30 minutes.
Cool completely on rack.
Cut into 1-inch cubes.