INSTRUCTIONS
1. Preheat the oven to 350°. Butter a 9-inch springform pan. In a large bowl, whisk the flour, pumpkin spice and salt. In a medium bowl, whisk the syrup, oil and egg. In a glass cup, stir the hot water with the baking soda. In 3 alternating additions, whisk the syrup mixture and soda water into the dry ingredients.
2. Scrape the batter into the pan and bake for 40 minutes, until a cake tester inserted in the center of the cake comes out clean. Transfer the cake to a rack and let cool.
3. In a saucepan, combine the stout, triple sec and honey. Boil until reduced to 3/4 cup, about 15 minutes. Pour into a shallow dish, let cool in refrigerator.
4. In a bowl, using a handheld mixer, beat the egg yolks and sugar until light and fluffy, about 5 minutes. Beat in the mascarpone. Whip cream and vanilla in a separate bowl until soft peaks form, then fold gently into mascarpone mixture until combined. If using food coloring, scoop some cream mixture into a separate bowl and add a few drops, stirring, then adding more food coloring until you get desired color.
5. Use a round cookie cutter to cut out circles in cake about the size of your jar. Gently dip the slices into the reduction and place in the bottom of 6 mini mason jars (if using mini plastic cups, cut the cake rounds in half before dipping). Dip the scraps into the reduction and use to fill in the gaps. Spoon some of the filling over the cake in each ramekin, spreading evenly. Repeat the layering of dipped cake and filling. Cover and refrigerate overnight.
6. Before serving, let the tiramisu stand at room temperature for 15 minutes. Sift cocoa powder over each jar and serve.