Bill Belichick's proving he can be a sweet boyfriend ... showering his love Jordon Hudson in delicious desserts -- though he may be a little late on the celebration.

The legendary head coach's girlfriend shared a picture from their anniversary dinner Friday night ... featuring a chocolate cake with "Happy Anniversary" written in white frosting.

The plate's got a candle and a few other goodies on it ... and, Jordon added her own twist by writing in brown script text on the photo "better late than never" with a matching heart after it.

The message here ... it sounds like this isn't her actual anniversary with Bill -- but, hey, they got to it eventually!

Looks like the two spent the whole night together too ... 'cause Jordon shared a pic of the University of North Carolina's stadium this morning too -- wishing the whole campus a "good morning."

As you know ... Bill recently took the job as the University of North Carolina head coach -- after discussing the gig with UNC legend Michael Jordan.

Bill's been working as a commentator since leaving the New England Patriots in January 2024 -- and, he's also spent a ton of time with Jordon. We broke the story about the two of them in June ... revealing they met on a flight from the Boston-area to Florida in 2021.

Looks like they're still going strong ... enjoying some treats in their sweet relationship.