Heat olive oil in a large sauté pan over medium-high heat until shimmering. Pat the chuck roast dry and season with salt and pepper. Sear the roast on all sides for about 4-5 minutes until browned.
Reduce heat to medium and add sliced onions and a couple of pinches of salt and pepper. Cook for about 4 minutes until softened. Add garlic, tomato paste, brown sugar, Italian seasoning, garlic powder, onion powder, chili powder, and more salt and pepper; cook until fragrant.
Pour Worcestershire sauce and a few splashes of beef stock into the pan to deglaze it, scraping up browned bits from the bottom.
Transfer the onion and garlic mixture to the slow cooker along with carrots and potatoes. Pour in the remaining beef stock, ensuring everything is submerged, and add more salt and pepper on top.