Season the pork tenderloin with salt, pepper, thyme, and rosemary.
Heat olive oil in a skillet over medium-high heat.
Sear the tenderloin on all sides until browned.
Transfer the tenderloin to the crockpot.
In the same skillet, sauté onions and garlic until translucent.
Add Worcestershire sauce and chicken broth, stirring to combine.
Pour the mixture over the tenderloin in the crockpot.
Cover and cook on low for 6-8 hours or high for 4-5 hours.
Once cooked, remove the tenderloin and let it rest for 10 minutes.
Slice and serve, garnished with fresh parsley.