Instructions:
Heat oil in a pan over medium-high. Season the chuck roast with salt and pepper, then sear all sides until browned.
Place potatoes and carrots in the slow cooker. Season.
Lay the seared chuck roast over the vegetables. Sprinkle with onion powder or add sliced onions and garlic.
Spread the horseradish atop the roast.
Gently pour in the beef stock around the roast.
Cook on low for 8-10 hours or high for 4-6 hours, until the meat is tender.
For the Gravy:
Remove the roast and vegetables from the slow cooker.
In a saucepan, melt butter, stir in flour to form a roux.
Gradually whisk in 2 cups of strained cooking liquid from the slow cooker.
Cook until the gravy reaches your desired thickness.