Slumber party!

Busy mother-of-two Kourtney Kardashian had Kim Kardashian over for a sleepover Saturday, so her sister could spend some time with her nephew Mason, 2, and niece Penelope, 1 month.

PHOTOS: Kourtney's maternity style

"Slumber party with Mason and Penelope!" Kim, 31, tweeted Saturday. The next morning she shared a picture of Kourtney, writing, "I woke up this morning to this . . . gotta love Kourtney Kardashian making breakfast."

PHOTOS: Meet Penelope

In the hilarious photo, Kourtney, 33, wears a sock monkey hat and flashes the peace sign at the camera while standing by the stove cooking breakfast in her gourmet kitchen. The Keeping Up With the Kardashians star also has her daughter Penelope sleeping soundly in a sling around her stomach.

PHOTOS: Her Mexican babymoon

Kourtney recently told Us Weekly that she's "not really" thinking about losing the baby weight at the moment. 

"I gained nearly 45 pounds. I'm 5 feet tall, so that's a lot," she said. Her strategy for now? "While I'm here around the house, I just eat healthy."

This article originally appeared on PIC: Kourtney Kardashian Carries Baby Penelope While Cooking Breakfast for Kim Kardashian