Spread the Hokkaido pumpkin, cut into small pieces and boil in 100 ml of water for 20 minutes until the pumpkin is soft. Pour the mixture and seal well. Drain well using a sieve. Reserve 150 grams for the dough and weigh 125 grams for the frosting. The rest can be snow.
Butter two 15 cm diameter ovens. Preheat the oven to 175 degrees. In a bowl, mix the dark chocolate with the boiling water and stir until the chocolate melts. Add cocoa powder and stir until smooth. Then let it cool.
Sift the flour, starch, baking soda, baking powder, salt, sugar and a pinch of cloves into a bowl. In a second large bowl, beat eggs, vegetable oil and 150 grams of pumpkin using a clean hand mixer. Add the vanilla extract, buttermilk and the cooled chocolate mixture and continue to beat. Whisk in the flour and baking mix until well combined. It is important not to overstimulate. Divide the dough evenly between the prepared baking trays and bake for 30 minutes.
Grease a baking sheet for the nut cracker. In a heavy-bottomed, high-sided saucepan, add the sugar, water, maple syrup and butter and bring to a boil. Heat until the sugar melts and turns golden. Continue cooking until the caramel is light brown and the temperature reaches 148 degrees. Then remove from the heat, mix baking soda and finally the nuts. Mix well, then pour on the baking sheet. Cover the hot crumbs with chopped chocolate. Let the chocolate melt on top for a few minutes, then spread with a spatula and leave to cool. When it cools down, cut the dough into pieces. Finely chop a few pieces for the filling.
For the pumpkin and ermine frosting, put sugar, vanilla salt, spices and 125 grams of pumpkin puree in a pan with milk. Heat slowly until the sugar dissolves. Then sift the corn flour and allow the mixture to thicken over medium heat, stirring constantly to prevent burning. This will take a few minutes. As soon as the mass thickens like a pudding, remove the pan from the heat. Place the cream in a bowl and place a piece of parchment paper directly on top to prevent a skin from forming. Let the dish cool on a wire rack for about 20 minutes to allow air to circulate. Then cool and refrigerate for at least 30 minutes. Using a food processor or hand mixer, cream the butter until smooth. Gradually add the cooled pumpkin cream and continue beating vigorously until the frosting is very smooth.
Now assemble the whole cake: cut the bottom curves. Cut each base in half horizontally with a serrated knife. Place one half of the base on a plate, spread with some frosting and sprinkle with finely chopped breadcrumbs. Place the second half of the base, also dress with frosting and sprinkle with a little biscuit. Repeat the process on the second floor. The last lower half does not break. Cover the cake around with frosting and decorate the top with broken cones.