Cold-brine the brisket
Chop veggies fairly small, place in bottom of instant pot.
Preheat oven to 400 degrees.
Cut brisket into 2-inch pieces and brown in a pan with olive oil
Add brisket to instant pot.
Add broth, thyme, rosemary, bay leaves, and pepper to instant pot.
Cook on Stew for 1hr.
Poke potatoes with fork. Bake whole potatoes with olive oil and salt at 400 degrees for 1 hour.
Prepare garlic butter.
Set out potatoes to cool while instant pot is naturally decompressing. Scoop out middle section of potatoes and put potato scoop into a bowl.
Mix scoop and garlic butter.
Take out brisket and shred in a bowl. Put brisket into hollow potatoes.
Spread mashed potatoes on top as a cap.
Bake again until crispy.
Garnish with cooked veggies either on top of hollow potatoes or as a side on the mashed potatoes. Salt to taste.