Step 1

Spray 5-quart slow cooker with cooking spray.

Step 2

In 8-inch skillet, melt butter over medium heat. Cook onion and garlic in butter, stirring frequently, 2 to 3 minutes or until translucent and soft.

Step 3

In large bowl, stir onion mixture and remaining ingredients until well combined.

Step 4

Place in slow cooker. Cover and cook on Low heat setting 3 hours; stir. Cover and cook on Low heat setting 2 to 3 hours longer or until center of casserole reaches at least 165°F and edges are bubbly. Stir.