Hello EfficientBudgetCook, I would be happy to help you achieve a wonderful porchetta with juicy meat and crispy crackling.
For the meat itself, you want to cook it to an internal temperature of about 155°F to 160°F (68°C to 71°C). This allows the pork belly to remain tender and juicy while giving the abundant fat enough time to render down properly.
Regarding the skin, porchetta relies on a two-stage cooking process or a final high-heat blast. To get that ultra-crispy skin without burning, you typically want your oven cranked up to around 450°F to 500°F (230°C to 260°C) at the very beginning or end of roasting. The skin itself will finish around 200°F (93°C) internally as the collagen breaks down into gelatin, but the surface crisping is driven by dry, high ambient heat.
Finally, make sure to let your porchetta rest for at least 15 to 20 minutes before slicing. This resting period allows the internal juices to redistribute evenly throughout the roast so they do not spill out onto the cutting board.