Preheat the slow cooker on high for 20 minutes.

Spray the slow cooker insert with nonstick cooking spray.

Stretch, roll, and form the pizza dough to fit the slow cooker insert.

Ensure the crust is thin.

Place the dough in the cooker and spread it out evenly.

Cook on high, uncovered, for 1 hour.

Layer mozzarella slices over the dough, extending them up the sides.

Overlap the cheese slices in a circular pattern.

Cover the center with an additional cheese slice if needed.

Layer pepperoni slices over the cheese.

Spread a thin layer of pizza sauce over the pepperoni.

Sprinkle grated Parmesan cheese over the sauce.

Cook on high for another hour until the crust is caramelized and the bottom is firm.

Carefully remove the pizza from the slow cooker using a spatula.

Garnish with fresh basil chiffonade and crushed red pepper.