Preheat your oven to 350°F (175°C) and grease an 8-inch round cake pan with vegetable oil, lining the bottom with parchment paper.

Boil or roast 2-3 medium beetroots until tender, about 30-45 minutes, then cool and puree until smooth.

Whisk together 1.5 cups flour, 0.75 cups cocoa powder, 1 cup sugar, 1 teaspoon baking soda, and a pinch of salt in a large bowl.

In another bowl, beat 2 eggs, 0.33 cups oil, 1 teaspoon vanilla extract, and the beetroot puree until smooth.

Gently fold the wet mixture into the dry ingredients until just combined, avoiding overmixing.

Pour the batter into the prepared pan and bake for 30-35 minutes, until a toothpick comes out clean.

Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.