*Note: You can substitute 3 cups gluten-free, all-purpose flour plus 1 ½ teaspoon xanthan gum for every 3 cups regular all-purpose flour.
In a small bowl, thoroughly mix the cornstarch and water with a whisk or fork and set aside.
In a medium saucepan, whisk together the coconut milk, pumpkin purée, maple syrup, pumpkin pie spice, and salt, and heat over medium heat until it just begins to boil, about 5 minutes. Slowly drizzle the cornstarch mixture into the saucepan, whisking continuously. Let cook until the mixture becomes very thick in texture, about 5 minutes, whisking frequently.
Pour the crème into a bowl and let cool for about 15 minutes. Cover the bowl with plastic wrap so that the plastic wrap is touching the top of the crème. Refrigerate for a few hours or overnight.
Preheat the oven to 350 degrees. Lightly grease three 9-inch-round cake pans or one 9-by-13-inch pan and line the bottoms with parchment paper.
In a large bowl, whisk together the flour, sugar, baking soda, and salt. In a separate bowl, whisk together the milk, oil, vinegar, and vanilla. Pour the wet mixture into the dry mixture and whisk until just combined. Do not overmix.
Fill each prepared cake pan evenly with batter. Bake for 18-20 minutes, or until a toothpick inserted in the center of the cake comes out clean with a few crumbs clinging to it. Rotate the cakes halfway through the baking time. Cool the cakes completely before assembly.
In a small bowl, whisk the amaretto, water, and espresso until the espresso dissolves.
In a large bowl or trifle dish, place 1 layer of cake at the bottom and drizzle it with the espresso mixture. Spread a layer of pumpkin crème on top and generously sprinkle with ground chocolate. Repeat this process for 3 more layers until all of the components are used up. You could also cut the cake into mini rounds for individual servings in mini trifle dishes or ramekins.