Chief Keef's Birthday Cake is Over Being Sober

Chief Keef is so anti-sobriety even his birthday cake is under the influence.

The rapper celebrated his 21st birthday with a cake straight out of a stoner's dream -- edible blunts and a Promethazine bottle on a 3-tier cake. Settle down, lean users ... it's just a fondant decoration.

Cake and Art in WeHo made the sweet piece ... complete with edible frosting paper to recreate Bill Da Butcher artwork -- and the "gold" chains might look tough, but they're just buttercream.

For the record: No actual codeine syrup was included in the recipe.

We're told Marc Gravelle needed just 4 hours to create the dope cake, which set Chief back a cool $1k.