Melt the bittersweet chocolate and butter in a double boiler on medium heat.
Pour chocolate mixture into mixer with paddle attachment. Add sugar, flour, and
vanilla extract. Cream together on medium speed for 2-3 minutes or until well mixed,
making sure to stop and scrape bottom and sides of bowl.
Add the eggs slowly, and mix on medium speed for 2-3 minutes.
Add chips and mix on low for 1 minute.
Pour into an 8 x 12 x 2-inch pan, either lined with parchment paper or greased.
Bake at 350 degrees F for 20 minutes.
Rotate pan and bake for another 20 minutes or until done.
Cool before cutting.
Serve with vanilla ice cream, raspberry puree and chocolate sauce.