Make-ahead: cool waffles completely, then refrigerate up to 3 days or freeze up to 2 months with parchment between layers. Reheat in a toaster for the crispiest results, or in a 350°F (175°C) oven for 5–7 minutes. Swap cheddar for gruyère or pepper jack. Extra-crispy tip: keep cooked waffles warm on a wire rack in a 200°F (95°C) oven while you finish the batch.