Add the apples to a large bowl. Then, add in the brown sugar, lemon juice, water, cornstarch, cinnamon, nutmeg, and salt. Toss to combine.
⅓ cup brown sugar, 1 tablespoon lemon juice, 2 tablespoons water, 1 tablespoon cornstarch, 1 teaspoon cinnamon, ⅛ teaspoon nutmeg, ⅛ teaspoon kosher salt