Preheat the oven to 350oF. Line a 12-cup muffin/cupcake pan with cupcake liners.
Combine flour, pumpkin pie spice,cinnamon, baking powder, baking soda,and kosher salt in a large bowl. Whisk together and set aside.
In a separate bowl, combine brown sugar, sugar, pumpkin puree, and oil.Whisk together until combined and sugar begins to dissolve, about 2-3 minutes. Then add eggs, sour cream, and vanilla extract and continue to whisk until all ingredients are fully incorporated.
Add dry ingredients to the wet ingredients and fold together until just combined and there are no patches of flour in the batter.
Fill each cupcake cup until about3⁄4 full. Bake for 20-22 minutes, until a toothpick comes out clean. Allow the cupcakes to cool completely in the pan.Repeat with remaining batter.
While the cupcakes are cooling,make the cream cheese frosting. Add cream cheese to the bowl of a stand mixer fitted with the paddle attachment.Beat for 3 minutes, then add butter and continue to beat for another 2 minutes.
Scrape down the sides of the bowl,then add powdered sugar, meringuepowder, and cinnamon. Mix on low speed, then gradually increase to medium speed. Add a pinch of salt and vanilla extract. Continue to mix for 2 minutes
Optional: Make the caramel sauce(you can also use store bought).Add sugar to a saucepan and melt over medium heat, stirring every 30 seconds with a wooden spoon. When the sugar is fully melted, it will be brown and thick. Add butter and remove from the heat, gently whisking together until the butter is fully incorporated. Pour in heavy cream, mixture will separate. Add back to the stove over low heat. Whisk until everything comes back together, about 5 minutes - be careful not to burn.Add in kosher salt as desired.
Pour into a heat safe container and allow to cool until slightly thickened.
Using a knife to cut a circle into the center of the cupcakes to create a pocket, about 1 inch deep. Spoon about a teaspoon of buttercream into the center (more if desired), then place the removed piece of cupcake on top.
Add buttercream to a piping bag and pipe over the cupcakes. Then drizzle salted caramel sauce on top.