Step 1
Preheat oven to 350 degrees F (175 degrees C). Lightly grease a 9×13 baking dish.

Step 2
Combine the melted butter, sugar, and vanilla in a large bowl. Beat in the eggs, one at a time, mixing well after each, until thoroughly blended.

Step 3
Sift the flour, cocoa powder, and salt in a bowl. Gradually stir flour mixture into the egg mixture until blended. Stir in the chocolate morsels. Spread the batter evenly into the prepared baking dish.

Step 4
Bake in preheated oven until an inserted toothpick comes out clean, 35 to 40 minutes. Remove, and cool pan on wire rack before cutting.