Preheat oven to 275 degrees.
Trim any excess fat from the chuck roast. Peel the carrots and cut into 2 inch pieces. Cut the potatoes into halves or quarters so they’re all a similar size.
Heat a large dutch oven over high heat. Add 1 tablespoon of oil and heat until shimmering.
Place the chuck roast in the pot and sear on all sides. Remove the chuck roast and set aside.
Add the remaining tablespoon of oil to the pot. Once hot, add the carrots and let brown a bit, cooking for 2-3 minutes. Remove the carrots and set aside.
Add the beef broth and Worcestershire sauce to the dutch oven and deglaze the pan, scraping up any browned bits.
Add the ranch seasoning, au jus, pepperoncini, and pepperoncini juice and whisk together.
Return the roast to the pot. Add the carrots and potatoes, making sure everything is partially submerged in the liquid - it’s okay if the tops are sticking out.
Place the lid on the dutch oven and transfer to the preheated oven. Roast for 3 hours or until beef is very tender and falling apart.
Carefully remove the beef and vegetables from the pot and place on a serving platter.
To make gravy for the pot roast, remove any excess fat from the liquid in the pot.
Place pot on the stove over medium heat and bring to a low boil.
Whisk together the cornstarch with ¼ cup of water. Add this mixture to the pot of liquid and whisk well to combine. Continue cooking and whisking until gravy is as thick as you’d like.
Pour the gravy over the meat and vegetables and serve.