Preheat the oven to 325 degrees F. Line a baking sheet with parchment paper and spray with nonstick cooking spray.
Toss the walnuts, almonds, sunflower seeds, cinnamon and nutmeg together in a medium bowl. Add the maple syrup, butter and a pinch of salt, and toss to coat. Spread the mixture on the baking sheet and bake until golden brown and toasty, about 12 minutes, stirring once or twice. Cool on a baking rack.
Bring 2 cups water and 2 cups of the milk to a boil over medium heat, stir in a pinch of salt and the oatmeal and bring to a boil. Reduce the heat to low. Cover and cook, stirring occasionally, until thickened and the oats soften, about 30 minutes, adding more water if needed. Remove from the heat, and stir in the cherries and some hot milk to thin to desired consistency. Spoon the oatmeal into bowls and top with the yogurt and maple nut mixture.