Preheat oven to 177°C (350°F). Line muffin tins with 15 paper liners.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a small bowl, whisk together egg and egg whites, yogurt, and vanilla extract until smooth.
In the bowl of a stand mixer using the paddle attachment, cream butter until fluffy; about 2 minutes. Add the Redpath® Organic Granulated Sugar and blend until sugar is fully incorporated and the mixture is pale in colour; another 2 minutes.
On low speed, add a third of the egg mixture, increase speed to medium and cream until egg mixture is fully incorporated into the batter before adding another third of the egg mixture. Repeat the process with the remaining egg mixture, until just combined.
On low speed, add in half of the whisked dry ingredients and blend until just combined. Add in all of the milk, mix until just combined. Add in the remaining dry ingredients. Increase speed to medium and cream mixture until well combined; 2 minutes. Scrape down sides of the bowl every half minute.
Using an ice cream scoop or small ladle, fill liners about ⅔ full. Bake, until cupcakes are golden brown in colour, or until a skewer when inserted into the centre comes out clean with a few moist crumbs attached; about 18 to 20 minutes.
Allow cupcakes to cool in pan for 5 minutes before transferring them to a wire rack to cool completely before frosting.