Cake mixes can be expensive and with lots of added unpronounceable ingredients. I found this recipe for making brownies which is easy to make and great for kids to help with.
1 cup sugar
1/2 cup flour
1/3 cup cocoa
1/4 teasp. salt
1/4 teasp. baking powder
2 eggs
1/2 cup vegetable oil
1 teasp. vanilla
Sieve the first five ingredients into a bowl. Combine the last three ingredients together and add to the dried ingredients. No need to use a food mixer, just stir until blended and bake at 350 degrees for 20-25 minutes (a 9" square pan works well).
Enjoy.