Preheat oven to 350 degrees.
Grease and flour 3 x 7 inch cake pans, line bottoms with parchment paper.
In medium bowl add the flour, baking soda, salt, cinnamon, cloves, nutmeg, ginger. Stir with whisk to mix, set aside.
In bowl of mixer fitted with the paddle attachment add the eggs, sugar and oil. Mix on med-high speed for 5 minutes scraping down the sides of bowl as needed.
Bring mixer down to low speed, slowly add in the flour, scrape down side of bowl as needed.
Mix in the pumpkin puree and vanilla.
Mix all well to combine, about 1-2 minutes.
Scrape down sides of bowl if needed.
Pour evenly into three prepared pans.
Bake 25-30 minutes or until toothpick inserted comes out clean. Rotate cake pans half way through baking.
Mix butter on medium speed until light and fluffy.
With mixer on low speed add in the powdered sugar one heaping spoonful at a time. Alternate with caramel sauce. Add the salt, vanilla and bourbon. If needed (buttercream too thick) add in the milk 1 tbsp at a time until the right consistency is reached. (buttercream should be soft and spreadable but able to hold a shape if piped)
Scrape down the sides of the bowl as needed. Mix until completely smooth and creamy and well combined.
Cut humps off of cake layers if necessary and cut each layer in half horizontally so you have 6 cake layers (this is optional you can opt to not cut the cake layers in half for a 3 layer cake). Put a small smear of buttercream onto your cake board/plate (this will help keep the cake in place). Place the first cake layer on the cake board/plate.
Spread a large dollop of buttercream on top and spread evenly to the edges of the cake. Place next cake layer on top and spread with buttercream.
Repeat with with remaining cake layers until all are stacked. (NOTE - due to the moist nature of this cake the layers have a little weight to them and can break while moving/placing them so be careful of this by supporting them well while moving/placing them).
Once all the layers are in place apply a crumb coat of buttercream around the top and bottom of cake. Refrigerate at least 45 min. (Crumb coat gives a nice smooth base to work with when ready to apply final coat of buttercream and decorate).
Make your second batch of buttercream if needed. Apply final coat of buttercream.
If doing proceed with the piped border around the bottom.
Decorate with sprinkles, pumpkin and flowers.
Keep in cool dry place. If refrigerating take out 1 hours prior to serving.