• Preheat Oven and Prepare Pan: Preheat your oven to 350°F (180°C). Line an 8x8 inch baking pan with parchment paper, leaving some overhang for easy removal.
• Mix Dry Ingredients: In a large bowl, sift together the flour and cocoa powder. Whisk in both the sugars until well combined.
• Add Wet Ingredients: Make a well in the center of the dry ingredients. Add the melted butter and egg. Mix until combined into a thick batter.
• Fold in Chocolate Chips: Gently fold in the chocolate chips into the batter.
• Bake: Pour the batter into the prepared pan, smoothing the top with a spatula. Bake in the preheated oven for 20-25 minutes or until a toothpick inserted into the center comes out mostly clean with a few moist crumbs.
• Cool and Serve: Allow the chocolate slice to cool in the pan for about 10 minutes, then use the parchment paper to lift it out onto a wire rack to cool completely before making the icing.

Chocolate Icing

• Sift: Sift the powdered sugar and cocoa powder into a medium-sized mixing bowl to ensure no lumps.
• Add Liquids: Pour in the melted butter and boiling water. Whisk until the mixture is smooth and thick.
• Spread Icing: Pour and spread the icing over the completely cooled chocolate base.
• Set in Refrigerator: Place the slice into the refrigerator to set for 1-2 hours or until the icing is set.
• Slice: Once set, cut the chocolate slice into squares or desired shapes and enjoy!