This delicious sweet treat by Martha Stewart is a perfect way to use up any beets you may have in your fridge. You can’t taste the beets, but they add a nice pink-red hue to the cake. 
Ingredients:
- 4 medium beets, peeled, trimmed, and cut into chunks
- 2 cups flour
- 1 1/2 cup sugar
- 1 1/2 tsp baking soda
- 1/2 cup cocoa powder
- 1/4 cup olive oil
- 3/4 cup warm water (from the boiled beets)
- 1 tsp pure vanille extract
- 2 large eggs
Directions:
Cover beets with water in a pot. Bring to a boil. Reduce heat, and simmer until very tender when pierced with the tip of a sharp paring knife, about 30 minutes. Drain the beets BUT SAVE THE WATER. Puree beets in a food processor until smooth.
Preheat oven to 350 degrees. Whisk together flour, sugar, cocoa powder, baking soda, and 3/4 teaspoon salt in a large bowl. Whisk in eggs, water, oil, vanilla, and 1 1/4 cups beet puree (reserve remaining puree for another use).
Coat a 9-inch round cake pan (3 inches deep) with cooking spray. Line bottom with parchment, and coat with spray. Pour batter into pan. Bake until a toothpick inserted into the center comes out clean, about 45 minutes. Let cool in pan on a wire rack for 20 minutes. Turn out cake from pan, and discard parchment. Let cool completely, right side up.