Preheat oven to 325℉/160℃.  Grease a 12-inch round baking pan. 

In a large mixing bowl or stand mixer, add the butter and sugar. Use a hand mixer, whisk or stand mixer to beat the butter and sugar until fluffy.

Add the eggs, vanilla, baking soda, yogurt and salt. Mix until combined.

Add the flour gradually and mix just until combined.

Add half of the dough to greased 12-inch round baking pan and spread evenly.

Sprinkle the chocolate chips evenly across the tin, leaving an inch of dough around the edges. Place the rest of the dough on top to cover the chocolate chips and spread evenly.

Bake for about 45 minutes until a removed toothpick comes out clean.

Meanwhile, make the frosting by beating the cream cheese and the butter with a mixer or whisk. Add the powdered sugar and mix again until frosting is creamy and lump-free.

Remove half of the frosting and sift in the cocoa powder, to avoid clumps. Mix well.

Remove the GIANT cookie from the oven and allow to cool for about 30 minutes.

Spread the black and white frostings on each half of the cookie. It helps to take a piece of paper to mark the halfway line.