Preheat your oven to 375 degrees F and line a baking sheet with foil, parchment paper or a silicone baking mat. Set aside.
In a small bowl, whisk together the olive oil, dijon mustard, Italian seasoning and dash of salt and pepper. Rub the mixture all over the pork tenderloin.
Unroll the crescent dough onto your prepared baking sheet and do not separate along the perforations. Lay the pork on top and wrap the crescent dough around it to enclose. Press to seal any openings.
Bake the pork tenderloin for about 30-35 minutes or until a meat thermometer reads 140 to 145 degrees for medium to medium-rare.
Let rest for at least 10 minutes and then serve immediately, garnished with parsley if desired.
I find it very important to use a meat thermometer when cooking a pork tenderloin such as this. You don't want it overcooked as much as you don't want it undercooked. As every person's oven is different, the baking time will fluctuate.