Prep. Preheat oven to 325°F. Spray a 12 cup bundt pan with nonstick cooking spray; set aside.
Mix. In a large mixing bowl, using a handheld electric mixer, beat the sugar (2 cups), oil (1 1/2 cups), and eggs (3), until smooth. Mix in the apple cider (1/2 cup) and vanilla extract (2 teaspoons) until evenly combined.
Combine. In a medium mixing bowl, whisk together flour (3 cups), baking soda (1 teaspoon), salt (1/2 teaspoon), cinnamon (2 teaspoons), ginger (1/2 teaspoon), and nutmeg (1/4 teaspoon) until evenly combined. Gradually add the flour mixture to the sugar mixture and beat well. Fold in apples (2-2 1/2 cups) and walnuts (1 cup).
Bake. Pour into prepared bundt pan. Bake in preheated oven until a skewer or cake tester inserted in the center of the cake comes out clean, about 1 hour to 1 hour 20 minutes. Remove from oven and cool in the bundt pan, set on a wire rack for 15 minutes. Invert the cake onto a cake plate and cool completely.
Glaze. Bring condensed milk (1 (14-ounce) can) and brown sugar (1 cup) to a boil over medium-high heat, whisking almost constantly. Reduce the heat and simmer for 8 minutes, whisking often. Take off of the heat and stir in butter (2 tablespoons) and vanilla (1/2 teaspoon).
Drizzle. Cool for 5 minutes before drizzling on the cake.