Add ½ cup oil and 10 crushed garlic cloves to a large resealable bag.
Butterfly the pork and place in the bag. Seal, coat evenly, and allow to marinate for up to 4 hours.
Meanwhile, toast the remaining 12 garlic cloves in a skillet over medium heat until lightly browned and fragrant, about 8 minutes. Remove from skillet.
When cool enough to handle, peel 10 and mince. In a small bowl, combine minced roasted garlic with 1 tbs oil, red pepper flakes, thyme and ½ teas salt, ¼ teas pepper.
Mash with a fork to make a paste.
When ready to cook preheat the oven to 325 degrees F, remove the pork from the marinade and pat dry with paper towels. Smear the paste inside leaving a 1" border.
Securely tie using cooking twine. Season with salt and pepper.
Heat the skillet with the remaining 1 tbs oil over medium high heat. Add the pork roast and brown on all sides, about 10 minutes.
Place the pork on a wire rack on a rimmed baking sheet. Roast for 50 to 60 minutes, until it temps at 140 F at it's thickest point.
Mince the remaining 2 toasted cloves and add to a microwave safe bowl with the 2 tbs butter and ¼ sugar. Microwave until garlic is golden and butter is melted, about 1 minute.
Transfer the pork to a cutting boar and brush with the garlic butter. Cover and let rest for 20 minutes.
Slice and serve.