Preheat the oven to 350°F/180°C. Line a muffin tin with cupcake liners and set aside.
Add the flour, baking powder, salt, sugar, and butter to a large mixing bowl or the bowl of a stand mixer. Use a hand mixer or a stand mixer fitted with the paddle attachment to beat the mixture together until the butter has completely combined with the dry ingredients and no lumps remain. The texture will look sandy.
1 ¼ cup all purpose flour, 1 ½ teaspoon baking powder, ½ teaspoon sea salt, ¾ cup granulated sugar, ½ cup unsalted butter
Add in the eggs, lemon zest, lemon juice, vanilla, and buttermilk. Mix the ingredients together on low until a homogenous batter forms.
2 large eggs, 1 tablespoon lemon zest, 3 tablespoon lemon juice, 2 teaspoon vanilla extract, ½ cup buttermilk
Using a 3 tablespoon cookie scoop, scoop the batter into the muffin liners. Fill them each ¾ of the way full. Transfer to the oven and bake for 18-22 minutes or until a toothpick inserted in the center comes out clean with moist crumbs, never wet batter.
Remove the cupcakes from the oven. Allow them to cool to room temperature before frosting them.