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Using a stand mixer, beat 1/2 cup of softened unsalted butter until creamy. Gradually add 3/4 cup of granulated sugar and mix until light and fluffy. It's a good practice to scrape down the bowl to ensure even mixing. Follow with two room-temperature eggs, mixing well after each addition. Lastly, blend in 2 tsp of vanilla extract.
Now, mix your dry ingredients into the wet mixture in three parts, alternating with the sour cream/milk mixture. Start with a third of the flour, then add half of the sour cream, repeat until all ingredients are just combined. This careful mixing helps prevent a dense texture that can occur with overmixing.