Preheat oven to 350 degrees F. Butter two 6-inch round cake pans and line with parchment paper. Set aside.
In a medium bowl, whisk together flour, baking powder, baking soda, pumpkin pie spice, and ground cinnamon. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, cream together coconut oil and pumpkin puree. Add sugar, salt and eggs. Mix until smooth.
Add half of dry flour mixture. Mix on low speed until almost combined. Add milk. Mix on slow speed and then add remaining dry flour mixture. Mix until there are no longer any dry streaks of flour. Scrape down bowl as needed to ensure thorough mixing.
Divide cake batter between the two prepared cake pans. Level batter using a mini offset spatula. Bake for 35-40 minutes until toothpick inserted in center of cake comes out clean. Allow to cool in pan for 5 minutes before unmolding. Allow cake to cool to room temperature on wire rack.
In a heavy-bottomed sauce pot, melt butter over medium heat. Add corn syrup, brown sugar and salt. Stir together and bring to a boil. Continually stir the mixture to ensure contents do not burn along the sides of the pot.
Reduce heat to a simmer and allow mixture to cook for about 3 minutes. While the mixture simmers, whisk together the cream and cornstarch. Stir cornstarch mixture into the pot.
Increase heat and bring mixture back to a boil. Continue to cook and stir until mixture starts to thicken, about 2 minutes. Remove from heat and stir in vanilla. Transfer to a heat-proof container and allow to cool. Once cool to the touch, keep stored in the fridge until ready to use.
Cream Cheese Frosting:
In the bowl of a stand mixer fitted with a paddle attachment, cream together cream cheese and butter until smooth. Scrape down bowl as needed to ensure thorough mixing. Add powdered sugar, cooled butterscotch sauce, and salt. Mix until smooth.
Butterscotch sauce will thicken substantially in the fridge. Microwave for 15 second intervals to gently loosen the sauce and get it to a pourable consistency.