Potato Stack Scalloped Potatoes

Name: Potato Stack (Scalloped Potatoes)
Ingredients: 1 large russet potato; 2 small red potatoes; 2 tablespoons unsalted butter; 3 pieces garlic cloves; 2 teaspoons dried rosemary; 1/4 cup plus 2 teaspoons grated Parmesan cheese, divided; 1/4 cup whole milk, or 3 tablespoons skim milk; 1 teaspoon whole peppercorns; 2 teaspoons salt