Preheat oven to 350 degrees. Grease and flour 2 9-inch cake pans.
Add the eggs, sugar, oil, and vanilla to a large mixing bowl and beat together on medium speed until smooth and creamy. Stir in the pumpkin.
Add the flour, pumpkin pie spice, baking powder, baking soda, and salt to the bowl and beat together until well combined.
Pour batter into prepared cake pans and bake for 25 minutes or until a tester comes out clean.
Cool cake completely before frosting.
For the frosting:
Add the butter, cinnamon, and vanilla to a large mixing bowl and beat with an electric mixer until smooth.
Add the powdered sugar and cream and beat on low speed until incorporated. Increase speed to medium and continue mixing until the mixture is light and fluffy. Add additional cream to reach the desired consistency, if needed.
Spread 1 cup of frosting between the cake layers and frost the tops and sides of the cake. Sprinkle with cinnamon, if desired.