Using a funnel, layer the jar ingredients in a quart size canning jar in the order listed. The walnuts are optional.
If using walnuts, use enough to fill the jar to the top.
If you do not use the walnuts, use extra chocolate and vanilla chips so the jar is full to the top.
Pack down all ingredients, especially the brown sugar.

To make the brownies, preheat oven to 350 degrees. Grease one 9 x 9 inch square baking pan.
Pour the contents of the jar into a bowl and mix well.
Add vanilla, vegetable oil and eggs. Beat just until combined.
Pour the batter into the prepared pan. Bake for 25 to 30 minutes