Preheat oven to 350 degrees F. Spray 8x8 pan with nonstick spray, set aside. In a small bowl, combine the boiling water and baking soda; set aside. In a large bowl, sift together flour, baking powder, ground spices, and salt; set aside.
In a bowl of an electric mixer fitted with the paddle attachment, cream butter until light. Beat in brown sugar until fluffy, 1 to 2 minutes. Beat in molasses, baking-soda mixture, and flour mixture, then beat in eggs.
Pour into the prepared pan and bake for about 25-30 minutes, or until a toothpick inserted in the center comes out clean. Let cool completely before building the trifles.
Make the yogurt mixture: Combine all ingredients completely and set aside or refrigerate until ready to build trifles.
To build trifles, cut the cake into small cubes. Place one layer of cubed cake on the bottom of a small trifle dish. Line the outside of the dish with gingerbread man cookies or gingersnap cookies.
Spoon yogurt mixture into the dish, ensuring that it pushes through the spaces between the cookies - so you can actually see the yogurt.
Top with a few crumbled cookies and another layer of cake cubes. Top with another layer of yogurt and garnish with one more gingerbread man and some cookie crumbs.