Slow Cooker Whole Chicken

celery ribs (cut into 2-inch pieces)

carrots (peeled and cut into 1 ½ inch pieces)

red onion (peeled and cut into 8 wedges)

red potatoes (cut into 1-inch pieces)

garlic cloves (peeled and smashed)

sprigs of rosemary

sprigs of thyme

kosher salt (plus more for seasoning)

paprika

black pepper (plus more for seasoning)

dried thyme (or 1 teaspoon chopped fresh)

olive oil (plus more for brushing)

to 5- pound chicken

unsalted butter

all-purpose flour