°1 cup sugar
°½ cup cocoa powder
°1 cup all-purpose flour
°2 teaspoons baking powder
°Half a tsp salt
°Half a C milk
°4 tsp melted butter
°1 L egg yolk
°2 tsp vanilla extract
°Half-sweet chocolate chip cup
°1 cup boiling water

* instructions:

1- Preheat the oven to 350 degrees Fahrenheit. Spray an 8-inch square baking tray with cooking spray. Whisking ½ C sugar with ½ C cocoa powder & set apart.
2- Mixing flour, rest of the cup of sugar, and rest of cup of cocoa, baking powder and salt in  bowl. Whisking milk, butter, egg yolks, & vanilla in  bowl to smooth. Stirring milk to the flour mixture to combined. Fold chocolate chips 
3- Use rubber spatula, scrape dough to  prepared pan also distribute it on corners. Sprinkling cocoa blend also reserved sugar on top. Sweetly pour boiling water on cocoa. Don't moving.
4- Baking until top of cake is cracked, the sauce is buble and toothpick is inserted to area of ​ cake and it comes out mostly clean, for 22-24 min.  Cooling on rack about at least 10 min. Serving something warm with vanilla & ice cream.

Enjoy !