Chewy Chocolate Peanut Butter Chip Cookies

1 1/2 cups butter, melted
2 cups white sugar
2 eggs
1 teaspoon vanilla extract
2 cups all-purpose flour
3/4 cup unsweetened cocoa powder
1 teaspoon baking soda
1/2 teaspoon salt
2 cups peanut butter chips

1. Preheat oven to 350 degrees F (175 degrees C).
2. In a large bowl, mix together butter and sugar. Beat in eggs and vanilla. Combine flour, cocoa, baking soda, and salt; gradually stir into the butter mixture. Mix in peanut butter chips. Drop by rounded teaspoons onto ungreased cookie sheets.
3. Bake 8 to 10 minutes in preheated oven. Cool for 1 minute before placing on wire racks to cool completely.