Line the bottoms of two 8-inch cake pans with parchment paper and lightly butter.
Sift the flour, cocoa, baking powder, baking soda, and salt together. Stir the buttermilk, pumpkin, and vanilla extract together in a small bowl. Beat the butter and sugars together using an electric mixer on medium speed until light and fluffy. Beat in the eggs and yolk, one at a time. Reduce mixer speed to low and alternately beat in the flour and buttermilk mixtures in thirds.
Pour the batter into the prepared pans. Bake until a tester, inserted in the center, comes out clean--about 35 minutes. Cool layers completely before icing.
Beat cream cheese using a mixer set on medium-high speed until fluffy. Add confectioners sugar, cinnamon and vanilla and beat on low speed until well combined. In a separate bowl beat heavy cream confectioners sugar and orange food coloring on medium-high to soft peaks. Gently fold the whipped cream into the cream cheese mixture until well combinted. Spread 1 cup between the two layers and use the remaining for frosting the top and sides of the cake. cake. Chill the whole cake after frosting for 30 minutes.
Bring heavy cream to boil, pour over chocolate, butter and corn syrup. Let stand 3 minutes and whisk until smooth. Cool 3 to 5 minutes until the glaze thickens slightly. Pour the glaze onto the center of the frosted cake and smooth out to the edges to allow the glaze to drip over the sides.