Rich & Creamy Gluten-Free Tiramisù (no ladyfingers)

0 Make the chiffon cake batter and pour into an ungreased 8-inch square pan lined on the bottom with parchment paper. The cake batter will grip the sides of the pan as it bakes, helping it to rise high. Let cool completely in the pan.
1 Use a small offset spatula to loosen the edges of the cake. Turn out onto a cutting board and peel away the parchment paper. Turn right side up. Cut the cake in half, then cut crosswise into 1⁄2-inch thick slices.
2 Stir together the coffee, booze, and 2 tablespoons of the sugar until the sugar is dissolved.
3 In the bowl of a stand mixer fitted with the whisk attachment, whip together the mascarpone, cream, vanilla, ¼ cup sugar, and salt until the mixture just holds firm peaks. Cover and chill until needed.
4 Lay 1 layer of cake slices cut side up in an 8- or 9-inch square pan or the equivalent. Drizzle with half of the coffee syrup. Spread the soaked cake with half of the whipped mascarpone and grate a good layer of chocolate directly over the cream, about 1 ounce (28 g).
5 Repeat the layering process once more. If you like, use a large, plain pastry tip to pipe on the top layer of mascarpone. Top with more grated chocolate.
6 Serve right away with a spoon, or chill for 1–2 hours or up to 1 day and cut into slices to serve.