Food Network shows you how to make Crispy Potato Stacks. Add thinly sliced sweet potatoes and russet potatoes to a bowl, then add melted unsalted butter, sage, thyme, garlic, kosher salt and fresh ground black pepper. Use tongs to mix all ingredients. Add alternating slices of sweet potato and russet potato to each cup of a muffin pan, stacking to one inch above the tin. Bake for 25 minutes at 425 degrees Fahrenheit. Let cool for five minutes, top with freshly grated Parmesan cheese and enjoy.