Skinny Cheesy Potato Casserole

INGREDIENTS

3 1/2 lb

russet potatoes, washed and peeled

1/2 cup

green onions, finely chopped

1 tbsp

butter, melted

2 oz

low fat cream cheese, softened

1 1/2 cups

plain non fat Greek yogurt

1/2 cup

skim milk

1 1/2 tsp

kosher salt

1/2 tsp

black pepper

3/4 cup

part skim mozzarella, divided

3/4 cup

sharp cheddar cheese, divided