Preheat the oven to 180C.

Put the chocolate, butter and instant espresso powder in a large bowl and set it over a saucepan of simmering water, stirring occasionally with a spatula, until the chocolate and butter are completely melted and smooth.

Meanwhile, stir the flour, salt, and cocoa powder together in a medium bowl, and line a 9×13-inch baking pan with parchment paper.

Turn off the heat, but keep the bowl over the water and add the sugar. Whisk until completely combined, then remove the bowl from the pan. The mixture should be room temperature.

Slowly add the 5 eggs one by one, and the vanilla extract, whisking each until combined. Do not overbeat the batter at this stage or your brownies will be cakey.

Sprinkle the flour, salt, cocoa powder mixture, and the bag of chocolate chips, over the chocolate mixture. Using a rubber spatula, fold until just a bit of the flour mixture is visible.

Pour the batter into the prepared pan and smooth the top. Bake in the center of the oven for 20 minutes, then another 5 minutes if needed.

Bake until a toothpick inserted into the center of the brownies comes out sticky, but firm.

Let the brownies cool completely in the pan, refrigerate overnight if you can, then cut into squares and serve.

1¼ cups all-purpose flour

1 teaspoon salt

2 tablespoons dark unsweetened cocoa powder

300g dark chocolate, coarsely chopped

225g unsalted butter, cut into 1-inch pieces

1 teaspoon instant espresso powder

2 cups sticky brown sugar

5 eggs, at room temperature

2 teaspoons vanilla extract

1 bag chocolate chips