Heat 1 tbsp of olive oil in large saute pan. Add spinach and cook, about 4 minutes. Set aside.
Place pork loin on cutting board. Butterfly the pork by slicing down the middle lengthwise about ¾ of the way through, being very careful not to go all the way through. Spread open like a book and pound with tenderizer until about 1.5 “thick.
Sprinkle both sides with salt and pepper. Evenly layer pork with cooked spinach, 6 whole garlic cloves, pepperoni slices, and cheese.
Roll up the pork lengthwise and secure by wrapping with kitchen string/twine. (You might lose some of your stuffing, simply stuff them back in once your pork is tied).
Heat remaining 2 tbsp of olive oil over medium-high heat in the same pan you used for the spinach. Add pork (seamed side down) and cook 3 minutes per side or until golden brown. Place pork in bottom of your slow cooker.
In medium sized bowl mix together crushed tomatoes, onions, carrots, potatoes, beans, garlic powder, Italian seasoning, and crushed red pepper.
Pour tomato sauce mixture over pork, cover and cook on low 8 hours.
Remove kitchen string, slice and serve.