Preheat your oven to 350°F (175°C). Grease and flour two 9-inch cake pans.

In a large bowl, cream together the unsalted butter, granulated sugar, and brown sugar until light and fluffy.

Beat in the egg and vanilla extract, mixing until combined.

Slowly add the buttermilk, then stir in the flour, cocoa powder, baking soda, cinnamon chips, and salt. Blend until just combined.

Divide the batter evenly between the prepared pans. Bake for 25-30 minutes, or until a toothpick inserted comes out clean. Let it cool in the pans for 10 minutes before transferring to a wire rack.

In a small bowl, hydrate the gelatin according to package instructions with cold water.

In another bowl, whip the cold heavy cream until stiff peaks form.

Melt the semi-sweet chocolate in a microwave or double boiler until smooth. Let it cool slightly before adding it to the whipped cream.

Gently fold in the hydrated gelatin and pumpkin puree until everything is mixed evenly.

Place one layer of the cooled cake on a serving plate. Spread a layer of pumpkin mousse on top.

Add the second cake layer on top of the mousse, pressing gently then refrigerate for about an hour to set.

Drizzle with salted caramel sauce and top with butterscotch chips.

To create a ganache, heat heavy cream (1 cup) gently and then add to melted chocolate, stirring until smooth.

Pour over the cake layer once it has cooled a bit.

Allow the cake to cool completely before slicing.