Step 1

Melt butter in a large skillet over medium heat.

Step 2

Add onions and a pinch of salt and cook, stirring occasionally until tender, about 15-20 minutes.

Step 3

Add balsamic vinegar and cook for 1-2 minutes longer.

Step 4

Season chicken breasts with salt, pepper, thyme and garlic powder and add to slow cooker.

Step 5

Add onions and beef broth. Season broth mixture with additional salt and pepper to taste.

Step 6

Cover and cook on low for about 5-6 hours.

Step 7

Scoop out 1/4 cup of broth and add to a small bowl with flour. Whisk together until flour is dissolved. Stir mixture back into slow cooker and cook for another 15 minutes until broth slightly thickens.

Step 8

Meanwhile preheat oven to 350. *** See below.

Step 9

Transfer chicken and onion mixture to a baking dish.

Step 10

Top with shredded cheese and bake in the oven for 10-15 minutes until cheese is melted.

Step 11

Sprinkle with croutons on top before serving.

Step 12

***Alternatively you can top with cheese in slow cooker, increase heat to high. Cover and cook until cheese is melted.