In a standing mixer fitted with the paddle attachment, beat the butter and sugar on medium speed until creamy, about 2 – 3 minutes. Add eggs and vanilla, then mix until combined scraping down the sides of the bowl with a rubber spatula as necessary. Add 1/3 of the flour mixture and mix until mostly incorporated. Mix in half of the sour cream. Continue alternating ingredients (flour, sour cream, flour) until fully incorporated.