To color the sugar: Divide the sugar into 4 (1/2-cup) portions. Put 1/2 cup sugar into the jar and add 1 to 3 drops of food coloring. Put the lid on and shake the jar well until the sugar is completely colored. Empty the sugar into a small bowl and continue with the remaining sugar using different food colorings to make different colors.
To make the Sand Art: Whisk together the flour and salt and set aside. Layer the dry ingredients into the jar, alternating colors (the sugar) and dark (cocoa powder) and light (flour), making your own design. Don't forget the chips! Screw on the lid and print out this recipe to enclose with your gift jar.
To bake: Heat the oven to 325 degrees F. Grease a 13 by 9-inch pan with butter.
Dump the contents of the jar into a large bowl. Mix together the melted butter, eggs, and vanilla. Stir the wet and dry ingredients together until well combined. Pour the batter into the prepared pan and bake for 30 to 35 minutes.