1. In a large bowl, stir together the first five ingredients. Use a pastry cutter or fork to cut in the butter until the mixture resembles coarse crumbs. In another bowl, whisk together the egg and buttermilk. Combine the two mixtures and stir until well blended. The batter will be thick.
2. Coat a waffle iron with cooking spray and heat it according to the manufacturer's instructions. Ladle on 1/3 cup batter (the amount may vary depending on the size of your iron). Cook until golden brown, about 5 minutes. Repeat with the remaining batter. Serve each waffle topped with one quarter of the spinach and rotisserie chicken, and a drizzle of the maple sauce.For the maple sauce:
3. Whisk together the ingredients in a medium saucepan and place over high heat. Bring the mixture to a boil, reduce the heat to medium-high, and simmer uncovered until reduced by half, about 7 minutes.