Preheat oven to 350°F.
Heat a heavy pan with 3 tbsp of oil.
Season the roast with the salt and pepper.
Sear the meat in the pan. When the meat is nice and brown remove the meat.
Add the garlic, stew mix and brown.
Add the meat back to the pot with the beef stock, cover with a lid and cook in the oven for 1.5 hours.
In a blender, combine milk, eggs, egg yolk and flour. Blend until smooth.
When pot roast is tender, remove from the oven and then turn the oven up to 425°F.
Place a dry muffin pan into the oven while the oven is heating up. (You want the pan HOT!)
Put 1 tsp of oil in each muffin pan divot and put back in the oven for 1 minute to heat up.
Remove the muffin pan from the oven and fill each divot halfway with batter and place back into the oven. Let raise and cook until golden brown. About 5-8 minutes.
Remove the pot roast jus and add the peas to the hot vegetables.
Whisk in the mustard into the jus and adjust the seasoning.
Slice the pot roast, and serve with pot roast vegetables, yorkies and the mustard jus.