Beat the butter and sugar in the bowl of a heavy-duty electric mixer fitted with the paddle blade on high speed until light in color and texture, about 3 minutes. Beat in the eggs, one at a time. Scrape down the bowl and be sure the mixture is well blended. On low speed, add the flour in 3 increments, alternating with 2 additions of the milk, beginning and ending with the flour, and beat until smooth, scraping down the sides of the bowl often with a rubber spatula. Beat in the lemon juice, lemon zeset and vanilla. Using about 1 ¾ cups for each layer, spread the batter evenly in the pans.