15min porter (one US gal)

https://byo.com/article/create-your-own-great-porter/ - mostly based on the basic porter in this article with a bit more specialty grains

https://byo.com/article/practical-porter/

• The amount of crystal malt in porter recipes varies, but from 0.5 lb. (0.23 kg) to 1.25 lbs (0.56 kg) is typical
  
• Brown porters usually contain between 0.5 lbs. (0.23 kg) and 0.75 lbs. (0.34 kg) of dark grains, with chocolate malt being the most prevalent. Robust porters most often contain from 0.75 lbs. (0.34 kg) to 1.25 lbs. (0.56 kg) of dark grains per 5.0 gallons (19 L), with a substantial portion of the dark grain fraction being black patent.
  
  The Robust Porter features more bitter and roasted malt flavor than a brown porter, but not quite as much as a stout. Robust porters have a roast malt flavor, often reminiscent of cocoa, but no roast barley flavor. Their caramel and malty sweetness is in harmony with the sharp bitterness of black malt.