Preheat oven to 350 degrees F. Line a 9-inch circle baking pan with aluminum foil and lightly grease with oil or butter, set aside.
In a large bowl, add the flour, cornstarch, baking soda, and salt. mix well.
Then, using a hand mixer, blend the butter and sugar until they are smooth and creamy, about a minute or so.
Next, stir in the vanilla and flax eggs and mix until smooth.
Add the dry mixture and mix until combined - the dough will be quite thick
Add 1 cup of chocolate chips. Mix well to spread the chips evenly through the batter.
Place the dough in the prepared baking pan. Sprinkle with extra chocolate chips and gently press them down.
Bake the cake for 20–24 minutes, until golden brown. Check if a toothpick inserted in the cake center comes away clean, free of wet batter, to verify the baking time was enough.