Preheat oven to 350 degrees. Spray a 12-cup Bundt pan with cooking spray; set aside.
Working over a large sheet of parchment paper, sift together flour, cinnamon, baking soda, and salt; gather sifted ingredients into center of sheet; set aside.
In the bowl of an electric mixer fitted with the paddle attachment, combine vegetable oil, sugar, and eggs; mix on high speed until lemon yellow.
Fold reserved parchment in half lengthwise; with mixer on medium speed, gradually shake in dry ingredients until just incorporated.
Add apples and, if desired, nuts, to batter; mix to combine. Add vanilla, mixing until incorporated.
Pour batter into prepared pan, and bake until a cake tester inserted in the center comes out clean, 75 to 90 minutes.
Remove from oven, and cool slightly on a wire rack.
Invert cake onto rack; turn cake right-side up to cool completely on rack, and serve drizzled with caramel sauce