1. In medium saucepan, cover beets with water by an inch. Place pot over medium high heat and bring water to a boil. Reduce heat to medium and simmer beets until they are soft enough to easily be pierced through the center with a knife, about 25 minutes. Drain beets and puree, adding a tablespoon or two of water to get them to puree smoothly, Add only what you need. Set beet puree aside to cool.
2. Preheat oven to 350°F. In large bowl whisk together eggs, oil and sugars. Add vanilla extract and beet puree and whisk to fully combine. Mix flour, cocoa powder, baking powder and salt into the wet ingredients. Stir in chocolate chips and walnuts of using. Pour the batter into 9x13 inch baking pan that has been sprayed with cooking spray or lined with foil or parchment. Bake about 30 minutes or until a toothpick inserted into the center of the brownies comes out clean but still moist. Cool brownies completely before cutting. They will keep in an airtight container for 3 days.