Rub the entire roast with salt and pepper, then sear it on all sides in a large skillet with a tablespoon of oil.
Add parsley, cilantro, shallot, lemon, salt and pepper, olive oil, and stock to the slow cooker and stir. Place the roast in the mixture and cover. Cook on high for six hours, or low for eight, until the meat shreds easily but is still moist. Flip the roast and stir occasionally.
Place two cups of liquid from the slow cooker in a small pot with butter and *cornstarch slurry. Simmer for 5-7 minutes until it begins to thicken, then whisk in cream.
Shred meat with two forks and add gravy when serving.
Notes
*For the cornstarch slurry, mix the 4 teaspoons of cornstarch with 1/8 cup of water and stir until smooth. This prevents lumps from forming in the gravy.