Preheat the oven to 350 degrees F. Line 24 muffin cups with paper liners.
Put the flour, baking powder and salt into the bowl of a food processor. Add the sugar and orange zest and pulse a few times to combine evenly. Add the butter and pulse until the mixture looks like coarse sand, with some pea-size bits of butter.
Whisk together the milk, vanilla and eggs in a small bowl or measuring cup with a spout. With the food processor running, pour in the milk mixture and process until smooth.
Divide the batter evenly among the prepared muffin cups, filling them two-thirds full. Bake until a toothpick inserted into the center of the cupcakes comes out clean and the tops spring back when pressed gently, 20 to 25 minutes. Cool the cupcakes in the pans on a rack for 10 minutes, then remove and cool completely.
For the meringue frosting:
Bring a few inches of water to a boil in a medium saucepan. Whisk together the egg whites, sugar, orange juice and zest, cream of tartar and salt in a medium heat-safe bowl. Set the bowl over the saucepan, making sure the bottom of the bowl does not touch the water. Continue whisking until the mixture is hot to the touch and the sugar dissolves, about 2 minutes. Remove the bowl from the saucepan and beat, using an electric mixer at medium-high speed, until the meringue is cool and holds a stiff peak, about 7 minutes.
Generously pipe or spoon the frosting onto the cupcakes. Sprinkle with orange zest.
When measuring flour, we spoon it into a dry measuring cup and level off the excess. (Scooping directly from the bag compacts the flour, resulting in dry baked goods.)
Copyright 2016 Television Food Network, G.P. All rights reserved.