Preheat oven to 350°F (176°C).
Butter a 8’’x8’’ baking dish.
Whisk ½ cup sugar with ¼ cup cocoa powder in a small mixing bowl and set aside.
Melt butter and chocolate chips together in a large mixing bowl. I put it in the microwave for 30 seconds before mixing together.
Slowly whisk in milk, egg yolk, and vanilla.
Add in flour, sugar, ½ cup cocoa powder, baking powder, and sea salt and give the dry ingredients a slight whisk to incorporate before mixing into the wet ingredients. This is the lazy method. Alternatively, you can whisk the dry ingredients in another large mixing bowl before combining into the dry ingredients.
Once the mixture is combined, add it to your greased baking dish and spread the batter to the edges, forming an even layer.
Evenly, top the batter with the cocoa powder-sugar mixture and then evenly add the boiling water right over the top of that. I know it sounds weird, but trust me, it’ll be magical.
Bake for about 25-28 minutes or until a toothpick inserted into an area at the edge comes out mostly clean.
Serve with homemade whipped cream or vanilla ice cream and enjoy!