1. In a large bowl, combine the flours, sugar, cocoa, and baking soda, and stir to mix well. Add the coffee or water and the milk and vanilla extract, and mix with a wire whisk until the batter is smooth. (The batter will be thin.)
2. Coat four 8-inch round pans with nonstick cooking spray. Divide the batter among the pans, and bake at 350°F for 18 to 20 minutes, or just until the top springs back when lightly touched and a wooden toothpick inserted in the center comes out clean. Be careful not to overbake. Let the cakes cool to room temperature in the pans.
3. Invert 1 cake onto a serving platter, and spread with 1/4 cup of the jam. Add the next two layers, spreading each with jam. Top with the final layer.
4. Place the whipped topping in a small bowl, and gently fold the yogurt into the topping. Spread the frosting over the sides and top of the cake. Chill the cake for several hours.