1-First, preheat the oven to 350 degrees F and line a cupcake pan with liners for easy removal.

2-Sift the flour, sugar, salt, baking soda, and baking powder into a large bowl, then whisk them together to combine the dry ingredients evenly.

3-In a separate bowl, whisk the sour cream, milk, vanilla extract, melted butter, and egg whites until they’re mixed well, even if it’s a bit clumpy at first.

4-Add the wet ingredients to the dry ones and whisk until smooth, making sure not to overmix to keep the batter light.

5-Scoop the batter into the liners, filling them about two-thirds full, then bake for about 18 minutes until the centers spring back when touched.

6-Let the cupcakes cool completely before adding frosting for the best texture.

7-Once your cupcakes are cooling, it’s time to make the frosting. Use a mixer with a paddle attachment to cream the room-temperature butter until it’s smooth and airy.

8-Gradually add the confectioners sugar in two batches, then mix in the salt, vanilla extract, milk, and heavy cream.

9-Beat everything until it’s fluffy and spreadable, then transfer it to a piping bag for decorating the cooled cupcakes.