Do I have to use pork belly?
Nope. Pork belly is the classic move for maximum crackling and rich slices, but a butterflied pork shoulder (Boston butt) works great. It is leaner than belly (but still nicely fatty), stays juicy, and is easier to find. Ask the butcher to butterfly it, or do it yourself with a long knife.
How do I actually get crispy skin?
Three things: dry skin, salt, and high heat. Pat the skin very dry, leave it uncovered in the fridge overnight if you can, and roast hot at the end. Also, avoid letting the skin touch wet filling. Score only the skin and fat, not deep into the meat.
Can I prep this ahead for a dinner party?
Yes. Season and roll it the day before, then roast the next day. Once cooked, porchetta holds well. Let it rest, then loosely tent with foil for up to 45 minutes. Skin is crispiest right after roasting, so time the final high-heat stage close to serving.
What internal temperature should I target?
It depends on the texture you want and the cut.
For sliceable porchetta-style roast: pull at 160 to 165°F in the thickest part, then rest. This gives you juicy, clean slices and enough heat to render a good amount of fat in belly.
For pull-apart shoulder: if you are using pork shoulder and want that shreddable, collagen-melted tenderness, keep roasting until about 190 to 200°F. That is a different vibe, still delicious, just less deli-sliceable.
Either way, remember carryover cooking. The center can climb a few degrees while it rests.