1. Preheat oven to 350 degrees.
2. Pour melted butter into a large bowl. Stir in the sugar and vanilla.
3. Beat in the eggs, one at a time.
4. Stir in the cocoa. Stir in the flour, baking powder, and salt. Beat well.
5. Pour batter into a greased 13x9x2-inch baking pan.
6. Sprinkle the chocolate and caramel pieces on top of the batter, and press in slightly.
7. Bake about 30 minutes, just until set.