1-Preheat oven to 350 degrees F. Spray an 8-inch square baking pan with cooking spray.
Whisk ½ cup sugar with ¼ cup cocoa powder and set aside.
2-Whisk the flour, remaining ½ cup sugar, remaining ¼ cup cocoa, baking powder, and salt in a large bowl.
Stir milk mixture into flour mixture until just combined.
Fold in chocolate chips (batter will be stiff).
3-Using a rubber spatula, scrape batter into prepared pan and spread into corners.
Sprinkle reserved cocoa and sugar mixture evenly over the top.
Gently pour boiling water over cocoa.
Do not stir.
4-Bake until the top of the cake is cracked, sauce is bubbling and a toothpick inserted into cakey area comes out mostly clean, about 22-24 minutes.
Serve warm with vanilla ice cream.