Cheesy Mashed Potato Puffs

Ingredients:

2 cups mashed potatoes (leftover or freshly made, cooled)

1 cup shredded cheddar cheese

1/4 cup grated Parmesan cheese

2 large eggs

1/4 cup milk

2 green onions, chopped (white and green parts)

1/2 teaspoon salt, or to taste

1/4 teaspoon black pepper, or to taste