1 cup all-purpose flour
1½ cups sugar
6 tbsp. plus ¼ cup unsweetened cocoa powder, natural or Dutch-process
1 tsp. baking powder
½ tsp. salt
2 large eggs, room temperature
2 tbsp. butter, melted
½ cup (125 ml) milk
1 tsp. vanilla extract
1 cup (250 ml) hot, very strong, great-quality brewed coffee
Adjust the rack to the centre of the oven and preheat to 350°F. Butter an 8-inch square cake pan or a 2-quart shallow baking dish.
Sift together the flour, 1 cup of the sugar, the 6 tbsp. cocoa, baking powder and salt.
In a medium bowl, mix together the eggs, melted butter, milk and vanilla. Stir the liquid ingredients into the dry ingredients until just combined. Spread the batter into the prepared pan.
Mix together the remaining ½ cup sugar and the ¼ cup cocoa powder and sprinkle evenly over the top.
Pour the hot coffee over the cake batter, then bake for 25 minutes, until it appears just set around the edges yet still slightly jiggly in the centre.