If the pork tenderloin is too long for your slow cooker, cut it in half. Otherwise, leave it whole.
In a small bowl, mix the garlic powder, parsley, salt, pepper, onion powder, and paprika. Rub the mixture over the pork tenderloin and place it in the slow cooker.
In a medium bowl, whisk together the chicken broth, balsamic vinegar, honey, ketchup, and cornstarch. Pour the glaze over the pork.
Cover and cook on low for 2-3 hours, or high for 1.5-2 hours, until the internal temperature reaches 150-160°F.
Let the pork rest for 5 minutes before slicing and serving.
Optional: To thicken the glaze, strain the sauce into a small pot, mix 1 teaspoon cornstarch with 1 teaspoon water, and stir it into the sauce. Cook on medium-high heat until thickened.
