In a bowl add the eggs and sugar and beat for a minimum of 5 minutes until very frothy, thick pale yellow mixture
After 5 minutes slowly add the oil and vanilla and beat for an additional 2-3 minutes
Add the dry ingredients and mix just until incorporated
Prepare marble swirl by mixing ⅓ cup batter with 2 Tbsp cocoa, 2 Tbsp sugar, and 2 Tbsp oil
Pour batter into a deep round pan
Bake at 350°F for 1 hour and 10 minutes
Let cool completely before removing from pan
