Start by beating the butter and sugar together until light and fluffy.
Add the eggs one at a time, mixing well after each, then stir in the vanilla extract.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add this mixture to the butter mixture, alternating with sour cream and milk. Stir gently until everything is just combined.
Grease and flour a 9×5-inch loaf pan, or line it with parchment paper for easy removal
Pour the batter into the pan, smoothing the top with a spatula.
Preheat your oven to 325°F. Bake the cake for 65–75 minutes, or until a toothpick inserted in the center comes out clean.
The low-and-slow baking ensures the cake bakes evenly without drying out.
Let the cake cool in the pan for 15 minutes before transferring it to a wire rack.
Allow it to cool completely before slicing.
