Melt 4 tablespoons of butter in a small pot over medium heat. Once melted, add ½ cup of light brown sugar. Stir to combine. Cook over medium heat for 3 minutes, stirring occasionally, until the sugar dissolves and the mixture darkens slightly in color.

Turn the heat to low and add the heavy cream and maple syrup. Whisk until smooth. Simmer for 1 minute. Add the crushed walnuts and stir until combined. Turn off the heat.

Pour the mixture into the prepared cake pan and smooth it into an even layer. Transfer to the refrigerator for 15 minutes.

Sift ¾ cup of all-purpose flour, 1 tablespoon pumpkin pie spice, 1½ teaspoons of baking powder, and ¼ teaspoon of kosher salt into a small bowl. Set aside.

Add 4 tablespoons of butter and ½ cup of light brown sugar to a large bowl. Use an electric hand mixer to cream them together. Add 2 eggs and beat until smooth.

Add the pumpkin purée and half of the sifted dry ingredients. Beat until just combined. Add the remaining dry ingredients and ¾ cup milk, along with 1 teaspoon vanilla extract. Beat until just combined. Don’t over-mix!

Remove the cake pan from the refrigerator. Pour the batter over the caramel and smooth it into an even layer.

Transfer the cake to the oven and bake for 50 to 60 minutes. The cake is done when it reaches an internal temperature of 200ºF to 205ºF. A toothpick inserted into the center may not be completely clean, so use an instant-read thermometer to determine doneness as opposed to the toothpick.

Let the cake stand at room temperature for 30 to 45 minutes. The cake should still be warm to the touch.

Place a large plate over the cake pan and carefully invert the cake onto the plate. Let cool completely before frosting.

Place 4 ounces of cream cheese, 4 tablespoons of butter, 3 tablespoons maple syrup, and ¾ teaspoon kosher salt in a mixing bowl and beat on medium speed until smooth. Add the powdered sugar and beat on medium speed until smooth.

Transfer the frosting to a piping bag fitted with a star tip and frost the cake. Alternatively, smooth the frosting over the cake with a spoon or rubber spatula.

Finish the cake with a sprinkle of cinnamon on top if desired before slicing. Enjoy!