Meatballs can be browned in a skillet for 2 minutes on each side for added color and flavor. However, if you are short on time, you can skip to step two.

Place the bell peppers, onions and mushrooms in the crock of a slow cooker. Season with salt and pepper to taste.

Arrange the meatballs over the top. Pour in the chicken broth.

Cook on low for 4 hours.

Preheat the broiler.

Before serving, butter and toast the hoagie buns.

Arrange about 3 meatballs into the center of each bun. Spoon the peppers, onions and mushrooms over the top.

Place one slice of Provolone cheese over the top of each sandwich. Place the sandwiches under the broiler and heat just until the cheese is melted, about 3-5 minutes.

Meatballs can be browned beforehand for added color and flavor. If you are short on time, skip to step two. Spray the insert of your Instant Pot with cooking spray. Select the SAUTE program. Press ADJUST to MORE. Once the Instant Pot is HOT add the meatballs in batches. Brown on each side about two minutes.

Add meatballs to the insert. Add the bell peppers, onions and mushrooms. Season vegetable with salt and pepper to taste.

Pour in 1 cup of water.

Secure the lid. Make the sure the vent is set to SEAL. Select the MEAT/STEW setting. Press ADJUST to MORE. Set time for 7 minutes.

Let the steam release naturally.

Preheat the broiler.

Before serving, butter and toast the hoagie buns.

Arrange about 3 meatballs into the center of each bun. Spoon the peppers, onions and mushrooms over the top.

Place one slice of Provolone cheese over the top of each sandwich. Place the sandwiches under the broiler and heat just until the cheese is melted, about 3-5 minutes.