He's being such a good dad!

Reformed party boy Scott Disick took his little Dark Knight to Menchie's in Calabasas on Thursday -- and his lil' bat boy, Mason, looked oh-so adorbs in his jammies!

For the daddy duty, Scott opted for hoodie and grey jeans and white shoes -- and a huge scowl. Smile Scotty, you're back together with your lady love!

Kourtney and Scott have been back together for a few months, according to E! News The outlet also says that despite getting back together, they aren't living together ... yet.

After breaking up due to Scott's partying and messing around, Kourt reportedly finally took him back after he's worked to change his wicked ways.

"Scott has just been over the partying. He got sick of it and decided to clean up his act," the insider said. "He was having people over at his house to party until 6 a.m. all the time, and he hasn't been doing that either."

The two took a long time away from each other, but couldn't keep away. The source said, "Their love for each other never went away. He's been trying to win Kourtney over for a while now, but his constant partying was a huge issue."

The insider added, "He's been spending a lot more time with Kourtney and the kids and proving himself to show that his family is the priority."

Lord Disick may not be smiling -- but at least he's spending some quality time with his son!