Start by patting your chuck roast dry with paper towels. This will help create a nice sear. Rub your homemade seasoning blend all over the roast, making sure to cover all sides.
In a skillet over medium-high heat, add the avocado oil. Once hot, sear the roast for 3-4 minutes on each side until it’s golden brown.
Place the chopped onions, carrots, and potatoes in the bottom of your slow cooker, seasing with a little kosher salt and pepper if you like, toss.
Once your meat is done searing, remove it from the pan and set aside.
To the pan add the butter and the remaining seasoning blend, minuse the bay leaves and onion and cook stirring for 3 minutes.
Add the garlic, worstershire sauce, and beef stock.
Whisk well and remove from the heat.
Pour half of the sauce over the vegetables, top with the chuck roast, and pour the remaining sauce over. Add the bay leaves and rosemary.
Cook on high for 4 to 5 hours or low for 6 to 8 hours.