Preheat your oven to 350ºF and prepare a cupcake tin with 12 paper liners.
In a medium bowl, mix your flour, baking powder, and salt together and set aside.
In the bowl of a stand mixer with the paddle attachment, cream the butter and sugar together on medium speed until fluffy.
Add the egg and egg white and mix until combined, then add the oil, vanilla, and lavender and mix until combined.
Add the dry ingredients to the wet ingredients and mix until combined. Lastly, add the milk and mix on low-medium speed until just combined.
Use a ½ cup cookie scoop to portion your cupcake batter into each paper liner. Bake cupcakes for about 20-25 minutes or until a toothpick comes out clean. Let cupcakes cool completely before filling.