Preheat the oven to 350F. Line a cupcake pan with paper liners and set aside.
In the bowl of a stand mixer fitted with the paddle attachment, combine the cake flour, sugar, baking powder, cinnamon and salt and mix on low speed for a minute to combine.
1 ½ cups cake flour, ¾ cup granulated sugar, 2 teaspoons baking powder, ½ teaspoon fine sea salt, ½ teaspoon cinnamon
With the mixer still running, add in the softened butter pieces. Mix on low speed until the mixture resembles coarse crumbs.
5 tablespoons unsalted butter, room temperature
In a measuring cup, whisk together the egg, egg white, canola oil and vanilla.
1 large egg, 1 large egg white, 2 tablespoons canola oil, 2 teaspoons pure vanilla extract
With the mixer still on low, slowly pour in the milk, mixing JUST until the flour mixture is moistened. You may not use all the milk at this time. Pour any remaining milk into the measuring cup with the eggs and oil, and whisk to combine.
½ cup whole milk
Turn the mixer speed to medium and whip for a full 90 seconds. The mixture should be whipped up, thick, and lighter in color.
Scrape the sides and bottom of the bowl to ensure everything is properly mixed. With the mixer speed on low, add the egg/oil/remaining milk mixture in two additions, scraping down the bowl after each addition has been mixed in.
Once all the wet ingredients have been added, give the bowl a final scrape and mix with a spatula. Divide the batter evenly between the liners, filling them about ⅔ full.
Bake the cupcakes for 16-19 minutes, until a toothpick comes out with few moist crumbs when inserted in the center of the cupcake. Don't over bake.
Place the baked cupcakes on wire racks to cool for 5 minutes. Carefully remove the hot cupcakes from the pan and cool completely on a wire rack.