In medium bowl combine eggs and cream; whisk until well combined. Sprinkle onion powder, salt and both peppers over egg mixture while whisking. Whisk until completely combined. Set aside.
In slow cooker, combine hash browns and about 1/2 of each of Parmesan cheese, mozzarella cheese, sausage, sun-dried tomatoes and basil. Using fingers, gently toss until combined. Pour egg mixture over top; if necessary use spatula to smooth out top.
Set aside about 1/2 of remaining mozzarella cheese (approximately 2 ounces). Sprinkle remaining ingredients over top of casserole. Cover slow cooker and cook for 6-8 hours on low or until center is cooked through. A thermometer inserted into center should read 160 degrees F.
Sprinkle casserole with remaining cheese, serve and enjoy!
