Step 1

Spray slow cooker insert with cooking spray.  Add vinegar, dried onion, garlic powder, red pepper flakes, chopped pepperoncini peppers, and banana pepper rings to bottom of slow cooker.  Stir to combine.

Step 2

Add beef chuck roast on top of spice mixture, season both sides with salt and black pepper.  Top with butter.

Step 3

Place lid on slow cooker and cook on LOW for 8 hours.  Remove beef from slow cooker and shred.  Return to slow cooker to soak up any residual juice and serve.