Read the passage.
Brownie cake recipe:
• 4 oz. unsalted butter
• 3 oz. flour
• 2 oz. cocoa powder
• 1/2 teaspoon salt
• 1/2 teaspoon baking powder
• 7 oz. granulated sugar
• 2 large eggs
• 2 teaspoon vanilla extract
Instructions:
1. Preheat the oven to 350 F. Line a cake pan with parchment and spray well with nonstick cooking spray. Whisk together all the dry ingredients—the flour, cocoa powder, salt, and baking powder−in a small bowl, and set it aside for the moment.
2. Cube the butter and place it in a medium saucepan over medium-low heat. Stir occasionally as the butter melts. Add the sugar and stir until it all melts.
3. Before the mixture comes to a boil, remove the pan from the heat and let it cool a little. Once it has cooled, add one egg at a time, and whisk well in-between. The initially grainy mixture should become shiny and smooth as you add the eggs. Add the vanilla and whisk well once again. Now add the ingredients from the bowl you set aside earlier and stir them in with a spatula.
4. Scrape the brownie batter into the prepared pan and bake it for 24 minutes until a toothpick comes out with just a few moist crumbs attached. Cool the brownie cake completely before proceeding.
When should the dry ingredients be added to the wet mixture?