1-First, preheat your oven to 350 degrees F and line a cupcake tin with liners to make removal a breeze. This simple start sets the stage for baking success and helps achieve even cooking.

2-Next, in a large bowl, sift together the flour, sugar, salt, baking soda, and baking powder to ensure everything mixes smoothly.

3-Separate the eggs, using only the whites for the cupcakes you can save the yolks for another recipe if you like. In another bowl, whisk the melted butter, egg whites, vanilla extract, sour cream, and warm milk until fully combined, creating a rich base for your batter.

4-Add the wet mixture to the dry ingredients and stir until smooth, being careful not to overmix to keep that fluffy texture. Fill the cupcake liners about 2/3 full with batter, then bake for about 18 minutes, or until the centers spring back when lightly touched. Once done, allow the cupcakes to cool completely before frosting to prevent any sogginess.

5-For the vanilla buttercream, start by creaming the room temperature butter in a stand mixer with a paddle attachment until it’s smooth and airy. Gradually add the sifted confectioners sugar in two batches, then mix in the salt, milk, heavy cream, and vanilla extract until the mixture becomes light and fluffy.

6-Transfer the buttercream to a piping bag and pipe it onto the cooled cupcakes for a professional finish.