Butter one side of sliced bread. Heat a skillet over medium-high heat and crisp the ham a slice or 2 at a time, 30 seconds on each side and let cool on towels. Add butter to skillet and saute apples to tender crisp. Season with cinnamon, nutmeg, and salt and deglaze with Calvados.
Assemble sandwiches with mild cheese, crispy Serrano ham, sautéed apples and Manchego. Grill in skillet over medium heat until golden, covered loosely with tin foil, then turn and press for 7-8 minutes.