Bring water and salt to a boil in a medium saucepan over medium heat. Add cornmeal in a slow steady stream, whisking constantly. Cook until beginning to thicken, stirring frequently, about 4 minutes. Reduce heat to low and cook, stirring often, 30 minutes.
Add syrup, cinnamon, orange zest, nutmeg, and milk; stir well. Cook another 30 minutes on low. Pour into parchment-lined 13x9 baking dish and cool to room temperature. Cover with plastic and refrigerate overnight.
Cut polenta into squares, then cut each square diagonally into triangles. Melt butter (2 tbsp per 4 triangles) in a large skillet. Dip both sides of each triangle in flour, patting off excess, then fry until crisp and brown on both sides. Dust with powdered sugar and serve with maple syrup and fruit.