We used self raising flour, which has both leavening and salt in it, as a shortcut ingredient to make these savory and fluffy waffles. A small bit of sugar in the batter doesn’t add detectable sweetness, but keeps the waffles moist and helps the exterior crisp up when cooking.
Preheat the oven to 225˚ F or 250˚ F (as low as your oven will go). Combine the melted butter, milk and eggs in a large bowl; whisk to combine. Add the flour and confectioners’ sugar and stir to moisten, then add the apple and cheese and stir until well blended. Set aside.
Heat a waffle iron according to the manufacturer’s instructions. Working in batches, lightly butter the waffle iron, then ladle in some of the batter. Close the iron and cook until the waffles are browned and crisp, 5 to 7 minutes. Remove to a baking sheet and keep warm in the oven while you cook the remaining waffles.
Meanwhile, mix the maple syrup and mustard together in a small bowl. Toss the greens with the vinegar, olive oil and a pinch each of salt and pepper in a large bowl. Divide the waffles among plates, along with the salad. Drizzle the maple mixture over the waffles or serve on the side for dipping.