Grandma’s Polish Perogies

Ingredients

• 4 1/2 cups all-purpose flour
• 2 teaspoons salt
• 2 tablespoons butter, melted
• 2 cups sour cream
• 2 eggs
• 1 egg yolk
• 2 tablespoons vegetable oil
• 8 baking potatoes, peeled and cubed
• 1 cup shredded Cheddar cheese
• 2 tablespoons processed cheese sauce
• onion salt to taste (optional)
• salt and pepper to taste