Step 1

Preheat the oven to 400 degrees F (200 degrees C).

Step 2

Place chicken bones, garlic cloves, carrots, celery, and onion on a baking sheet and drizzle with olive oil. Toss to coat.

Step 3

Roast in the preheated oven for 30 minutes, stirring halfway through.

Step 4

Transfer roasted bones and vegetables into a 6-quart slow cooker. Add vinegar, bay leaves, salt, and peppercorns. Cover completely with water and cook on Low for 24 to 48 hours, adding 1 to 2 cups more water during the cooking process, to keep bones submerged.

Step 5

Strain broth using a fine mesh strainer. Pour into jars and refrigerate until ready to use.