Preheat oven to 350℉. Line a 9-inch round pan with parchment paper and grease with avocado oil. (About 1/2 tbsp)
In a medium bowl using a hand or kitchen stand mixer, mix eggs (adding 1 at a time) with the sugar until pale and fluffy.
Next, add vanilla extract, avocado oil, and milk, and mix for another minute or until well incorporated.
Now, add bread flour, baking powder, and salt through a metal sieve, and gently mix until all ingredients are well combined.
Add ⅓rd of the batter (about ¾ cup) into a small mixing bowl, and add the cacao powder through a metal sieve to that batter. Stir with a spatula until well combined and set aside.
Pour the vanilla batter into the cake pan. Next, add 1 tbsp of the chocolate batter at a time to the vanilla mixture, spreading them out in different parts.
Make designs by taking a toothpick or a small spatula, and gently swirling the chocolate and vanilla together.
Sprinkle chocolate chips all over and bake at 350℉ for 25-30 minutes, or until a toothpick inserted at the center of the cake comes out clean.
