Former MLB player Royce Clayton spotted ex-Dodgers pitcher Scott Erickson chowing down on a burger and enjoying a beer in Malibu less than 24 hours after Erickson watched his then-lover, Rebecca Grossman, mow down two young brothers , according to a chilling courtroom testimony.

Clayton, 56, took the stand Friday in a civil trial against socialite Grossman and Erickson, who are facing a wrongful death lawsuit for the horrific Sept. 2020 deaths of 11-year-old Mark and 8-year-old Jacob Iskander.

The pair were allegedly racing as they drove off after a boozed-up lunch when Erickson swerved to avoid the kids and their mother Nancy, who were walking in a crosswalk in Westlake Village, California.

Rebecca Grossman, center, is serving 15 years to life in prison.…