For the plum sauce filling: Combine the plums, sugar, onions, vinegar, soy sauce, brown sugar, ginger, chile flakes and 1/2 cup water in a medium saucepan over medium heat. Bring to a low boil and cook, stirring constantly, until the plums are tender. Remove from the heat and let cool. Once cooled, transfer to a medium bowl, cover, and refrigerate overnight to firm up. (Makes 2 cups.)
For the almond cake: Preheat the oven to 325 degrees F. Line two 8-inch round cake pans with parchment paper.
In a stand mixer fitted with the paddle attachment, mix together the flour and eggs on low speed until fluffy. Continuing on low speed, mix in the salt, baking powder, vegetable oil, milk and almond extract until combined. Divide the batter evenly between the two prepared cake pans.
Bake until a toothpick inserted into the cake comes out crumb-free, 30 to 35 minutes. Let cool to room temperature.
For the ginger buttercream: In a stand mixer fitted with the paddle attachment, cream the butter and ginger on low speed until fully incorporated and smooth. Gradually mix in the confectioners' sugar until fully blended. Add the salt and milk, and mix on medium speed until the buttercream takes on a light and fluffy texture, about 5 minutes. (Makes 4 cups.)
Spread the plum sauce on top of the first cake layer. Stack the second cake layer on top. Decorate with the ginger buttercream.
This recipe was created by a contestant during a cooking competition. It has not been tested for home use.