Take the porchetta out of the plastic and leave it on a baking rack at room temperature while you prep the rest of the ingredients. Turn the oven on at 350F.
Peel and roughly chop the sweet potatoes and put them in a saucepan with a pinch of salt, covered with water. Bring to a boil and cook until very tender, around 20 minutes.
When the potatoes are soft, strain them from the water and put them back on the hot pan. Add the butter and the warm cream and mash until smooth. Season with salt and pepper.
Slice the guanciale into ½ inch strips and cut each strip on the short side into smaller strips.
Cook on low heat to render the fat and to get the guanciale crispy and golden brown.
Prepare the Brussels sprouts by washing them and cutting them in half. Season with salt, pepper, oregano, and a drizzle of olive oil.
Remove the crispy guanciale from the pan, turn the heat on high, and add the Brussels sprouts. Cook on the flat side for 5 minutes then add the stock and cook for 5 minutes more.
For the salsa verde, combine parsley, dill, garlic, vinegar, and ½ cup of water with a few ice cubes in a blender. Blend until smooth, then slowly add the olive oil to emulsify. Keep it in the fridge.
Cook the porchetta in the oven for 30 minutes at 350F. Then cook for 5 minutes on low broil to get the skin crispy. Serve right away.
Serve a thick slice of porchetta per person along with some sweet potatoes and Brussels sprouts topped with crispy guanciale. Finish with a generous drizzle of salsa verde.
