Spray insert of 6- to 7-quart slow cooker with cooking spray. Open and separate the refrigerated biscuits into 8 biscuits.

Cut each biscuit into 6 pieces; place in large bowl.

Cut 1 cup pepperoni slices into quarters. Place half of the quarters in bowl with biscuit pieces. Add 3 teaspoons Italian seasoning to bowl with cut biscuits and pepperoni quarters; toss to mix.

Place biscuit mixture as evenly as possible in bottom of slow-cooker insert.

Spread the pizza sauce evenly over top of biscuits, making sure to get some sauce around edges so that biscuits are not touching insert without sauce in between.

Sprinkle the shredded mozzarella cheese and remaining half of pepperoni over top, trying to keep cheese away from touching insert.

Cover top of insert with large paper towel. Place slow-cooker lid on top of paper towel. (This will prevent condensation from dripping onto biscuits during cooking.)

Cook on High heat setting 1 hour 30 minutes to 2 hour. (Not all slow cookers cook the same. Test for doneness after 1 hour and 30 minutes by inserting knife into center to make sure biscuits are fully baked; outer edge will be dark golden brown.)

Remove bubble-up bake from slow-cooker insert while warm to prevent biscuits from sticking to insert.

Serve warm