Courteney Cox -- Birthday lunch Date with David Arquette

Today is Courteney Cox's birthday ... and the former "Friends" star celebrated with a special lunch date with the man she's divorcing ... David Arquette.

The two got together at a restaurant in Malibu -- along with their daughter Coco -- just 1 week after David and Courteney filed divorce papers to end their marriage.

The two had previously vowed to keep the split super amicable ... and promised to remain best friends while raising their child.

So far, so good.