How to Make It
In a small bowl, whisk the gelatin with 2 tablespoons of water. In medium saucepan, whisk the lemon zest, lemon juice, sugar and egg yolks. Cook over moderate heat, whisking, until bubbles form around the edge of the mixture, about 3 minutes. Reduce the heat to a bare simmer and cook, whisking, until the mixture has thickened enough to coat the back of a wooden spoon, about 15 minutes. Whisk in the gelatin mixture. Remove the saucepan from the heat and whisk in the butter, one tablespoon at a time, until well incorporated. Strain the lemon curd through a fine sieve into a bowl. Press a sheet of plastic wrap directly on the surface of the curd and refrigerate until cold and firm, about 2 hours.
Preheat the oven to 375°. Butter the bottoms and sides of three 8-inch round cake pans. Line the bottoms with parchment paper, then butter the paper.
In a medium bowl, whisk the eggs, egg yolks, molasses and vanilla until smooth. In a small bowl, mix the buttermilk with 1/3 cup of hot water.
In a large bowl, sift the flour with the baking powder, salt, cinnamon, ginger, nutmeg and cloves. Add the brown sugar and mix very well. Add the 6 tablespoons of butter and the oil and beat until the mixture resembles coarse meal. While beating constantly, slowly drizzle in the egg mixture until incorporated, then beat in the buttermilk mixture, scraping down the side and bottom of the bowl as necessary.
Scrape the batter into the prepared cake pans and bake for about 20 minutes, until the cakes feel bouncy and a tester inserted in the centers comes out clean. Transfer the cakes to a rack and let cool for 10 minutes. Unmold the cakes and cool completely on the rack. Peel off the parchment paper.
Meanwhile, in a medium bowl, using a handheld mixer, beat the cream until medium peaks form. Whisk the lemon curd to loosen it, then fold the whipped cream into the curd. Chill until firm, about 1 hour.
Place 1 cake bottom side up on a cake plate and spread one-third of the lemon cream evenly on top, leaving a 1/4-inch border. Repeat with another cake layer and another third of the lemon cream. Top with the final cake and the remaining lemon cream. Refrigerate the cake until set, about 2 hours.