Preheat the oven to 325F. Line the cupcake pan with liners.
In a medium bowl, thoroughly mix 1 ½ cups all-purpose flour, 1 teaspoon baking powder, ¼ teaspoon baking soda, and ¼ teaspoon sea salt together. In another bowl, mix the ½ cup whole milk, ¼ cup freshly squeezed orange juice, and 1 ½ teaspoon vanilla extract.
In a stand mixer with the paddle attachment fastened, add ½ cup unsalted butter (room temperature)and ¾ cup granulated sugar and beat at medium speed for 3 minutes until the butter is light and fluffy. You may need to stop to scrape down the bowl frequently to keep the butter close in contact with the mixer.
Reduce the stand mixer speed to low, slowly add 1 whole egg and 2 egg whites, and beat for another 2-3 minutes until the egg and butter mixture are emulsified (mixed together as one). Scrape down the bowl once more.
While the stand mixer is still running on low, add half the dry ingredients followed by the wet ingredients, and then the remaining dry ingredients. Mix just until the batter comes together and there are no more remaining dry pockets.
Scrape down the bowl once more and fold in the ⅓ cup sugar-coated fennel seeds using a spatula.
Fill each cupcake tin ¾ of the way to the top with batter. This should be roughly ¼ cup (75g) of batter per cupcake.
Bake cupcakes for 20 minutes or until a toothpick inserted into the center comes out clean.
Let cupcakes cool completely before frosting.
Spread frosting on cake as desired and sprinkle with additional sugar coated fennel seeds.