1. Preparation materials: 70g dark chocolate, 100g unsalted butter, 2 eggs, 70g white sugar, 70g sifted low-gluten flour, 100g walnuts.

2. Melt dark chocolate over water. Melt unsalted butter over water. Beat the eggs evenly. Chop walnuts.

3. Add the chocolate to the butter and stir evenly, then add the eggs several times and stir evenly.

4. Add sugar and stir evenly. Then add low-gluten flour and mix evenly. Finally add the chopped walnuts and mix well.

5. Preheat the oven to 180°. Line a baking sheet with tin foil. Pour the chocolate brownie into the mold and smooth it out. Place in the oven and bake for 20 minutes.