Preheat oven to 350°F (175°C).

Melt chocolate and shortening in a saucepan over low heat, stirring constantly.

Remove from heat and mix in sugar, eggs, and vanilla until well combined.

In a separate bowl, stir together flour, baking powder, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Stir in nuts.

Pour batter into an ungreased 8x8 inch baking pan.

Bake for 30-35 minutes, or until a toothpick inserted into the center comes out with moist crumbs.