In a medium bowl, beat the remaining 10 tablespoons (142g) of butter and the granulated sugar, with an electric mixer at medium speed, until light and fluffy. Beat in the eggs and the egg yolk in 3 separate additions, making sure each one is incorporated before adding the next. Beat in the vanilla extract until well combined. On low speed, beat in the flour mixture in 2 separate additions, followed by half of the milk after each addition. Beat unit combined.