Vegan brownies
I have no idea how well these resemble the real McCoy, but they're tasty in their own right. And they contain chocolate, so I guess that's enough reason... The simplicity of preparation might be ideal for making them with kids. As the batter also doesn't contain any egg, anyone is free to lick the bowl clean.
2 cups all-purpose flour
2 cups sugar (including some vanilla sugar)
1 cup (dutch processed) cocoa powder
1 teaspoon baking powder
1/2 teaspoon salt
1 cup oil
1 cup water
Mix the solid ingredients together before pouring in the liquid ingredients. Mix into a nice batter. Pour the batter into an oiled tin (approx. 8x8 in.) and bake in an oven at 350 degrees Fahrenheit for about 30 minutes, or until a skewer inserted in the middle comes out clean.
Optional ingredients could be (upto) 1 cup of chopped nuts or some chili powder (I use 1/2 teaspoon, but as either the strength of your chili powder or your mileage may vary, try how much you like for yourself).