Beat together 16 tablespoons (1 cup) unsalted butter, at room temperature; 2 cups granulated sugar, and 1 teaspoon salt, first until combined, then until fluffy and lightened in color.
Add 4 large room-temperature eggs to the batter one at a time, beating well after each addition. Scrape the sides and bottom of the bowl once all the eggs have been added, and beat briefly to re-combine.
Stir in 2 teaspoons baking powder. Add 3 cups King Arthur Unbleached All-Purpose Flour in three parts alternately with 1 cup whole milk, starting and ending with the flour.