In a stand mixer with the paddle attachment, beat the cream cheese for 1 minute until smooth. Scrape down the sides of the bowl and add the butter. Beating for 1 to 2 minutes, until well incorporated. Next, add the brown sugar, pinch of salt and vanilla extract, and beat until well incorporated. On low speed, slowly add the powdered sugar. Scrape down sides as needed, add food coloring (if using), and beat until smooth. Spread on cake and enjoy!