Peel the onion and slice it into three thick rounds, keeping them whole rather than separating them into rings. Place them in an even layer at the bottom of a large slow cooker.

In a small bowl, mix the ranch dressing mix, Italian dressing mix, and beef gravy mix until well combined.

Place the chuck roast on top of the onion rounds. Sprinkle half of the seasoning mixture evenly over one side of the roast. Flip the roast over and coat the other side with the remaining seasoning mix.

Pour the condensed beef consommé over the roast.

Peel the potatoes and cut them into 1 ½-inch chunks. Arrange them around the roast in the slow cooker.

Peel the carrots, cut them into 1 ½-inch pieces, and place them on top of the potatoes.

Cover the slow cooker with the lid and cook on low for 8 to 10 hours, or on high for about 6 hours, until the meat is fork-tender.

Once cooked, remove the roast from the slow cooker and shred it into bite-sized pieces using two forks or tongs.

Set a mesh strainer over a heat-safe bowl and pour the cooking liquid through the strainer to remove any solid bits. For a smoother, less oily gravy, use a fat separator to skim excess fat before serving.

Serve the shredded beef alongside the potatoes and carrots, drizzling the strained gravy over the top.