Preheat your oven to 350°F (175°C) and grease two round cake pans.

In a large bowl, whisk together the flour, baking powder, and ground cinnamon.

In another bowl, beat together granulated sugar and unsalted butter until light and fluffy. Add eggs, pumpkin puree, and vanilla extract, mixing until smooth.

Gradually add the dry mix to the wet mix, combining until just mixed without overmixing.

Pour the batter into the prepared pans and bake for 25-30 minutes. Let cool for 10 minutes in pans before transferring to a wire rack.

To make the buttercream, beat softened butter until smooth, then add powdered sugar, vanilla, and ground cinnamon and mix until creamy.

Frost the first cake layer with buttercream, then add the second layer and frost the entire cake.