The Bojon Gourmet

Make the Cake
9 Position a rack in the center of the oven and preheat to 325ºF. Line the bottom of an 8-inch square cake pan with parchment paper and leave the sides ungreased. The cake batter will grip the sides of the pan as it bakes, helping it to rise high.
14 In a large bowl, whisk together the oil, water, egg yolks, vanilla, and ½ cup of the sugar until combined. 
10 Place a strainer over the bowl and sift the sweet rice and oat flours with the cocoa powder, baking powder, and salt directly into the yolk mixture, adding back any bits left behind in the strainer. Whisk until very smooth.
11 In the clean, dry bowl of a stand mixer fitted with the whip attachment, whip the egg whites with the cream of tartar on medium-high speed until soft peaks form. Slowly add the remaining 2 tablespoons sugar and whip until the whites are glossy and just hold a firm peak when lifted from the bowl and turned upside down, 1–3 more minutes.
12 Use a flexible silicone spatula to fold one-third of the whites into the batter, then gently fold in the remaining whites until just combined and no streaks remain. Immediately pour the batter into the prepared pan and quickly but gently use an offset spatula to spread the batter into an even layer.
13 Transfer the pan to the oven and bake until the cake springs back to the touch, and a toothpick inserted near the center comes out clean, 25-40 minutes. Remove to a rack and 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.
Assemble the Tiramisu
2 Stir together the coffee and booze. 
3 In the bowl of a stand mixer fitted with the whisk attachment, whip together the mascarpone, cream, sugar, vanilla, and salt until the mixture just holds firm peaks. Cover and chill until needed.
4 Place 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, then drizzle with half of the chocolate hazelnut spread. Spread half of the whipped mascarpone over the cake. 
5 Repeat the layering process once more. Top the tiramisu with the chopped chocolate and hazelnuts. 
6 Serve right away with a spoon, or chill for 1–2 hours or up to 1 day and cut into slices to serve.