In a small bowl, mix together flour and baking soda.

In a small saucepan, combine sugar, butter, and water. Bring to a boil over medium heat; remove immediately from heat.

Stir in 1 cup of chocolate morsels and vanilla extract until chocolate is melted and mixture is smooth.

Transfer mixture to a medium bowl. Cool completely.

Stir in eggs, 1 at a time, beating well after each addition. Gradually stir in flour mixture until smooth.

Stir remaining chocolate morsels and nuts into batter. Pour batter into prepared pan.

Bake until a toothpick inserted in center comes out clean, 30 to 35 minutes. Transfer pan to a wire rack to cool completely. Cut into squares.