I want to say right off the bat that this kway chap stall at Chong Boon hawker centre in Ang Mo Kio is slightly controversial. Some people found the food "bland" and the elderly stallholders a little brusque. Google review score is 2.4 ⭐ as at Oct 2023.
Stall name: Macpherson Hai Sing Kway Chap 麥波申海星粿汁
Address: 453A Ang Mo Kio Ave 10, Singapore 561453 (stall #01-27 inside Chong Boon Market & Food Centre)
Nearest MRT: 10 minutes walk from Ang Mo Kio station
Hours: 6am - 3pm (Thurs off)