Preheat oven to 350 degrees F.
Spray two 9" cake pans with cooking spray and dust with flour.
Combine flour, baking soda, salt, and cinnamon in a medium bowl, whisking to combine.
In a separate bowl, whisk together the eggs, sugar, oil, buttermilk, vanilla, carrot, and pineapple until well combined.
Add the flour mixture and stir until just combined.
Evenly divide the batter between the two pans.
Bake in preheated oven for 28-32 minutes, until a tester comes out clean.