-
Preheat oven to 325°F.
-
Line 8-inch square baking pan with foil, extending foil over sides.
-
Stir unsweetened chocolate and butter in a heavy large saucepan over low heat until melted and smooth.
-
Cool 5 minutes.
-
Whisk in sugar,cinamon, and salt.
-
Whisk in eggs, one at a time, then vanilla.
-
Continue to whisk until batter is smooth, about 2 minutes.
-
Add flour and whisk just until blended.
-
Stir in chocolate chips. Pour batter into prepared pan, smoothing surface.
-
Bake until tester inserted into center comes out with a few moist crumbs attached, about 35 minutes.
-
Cool completly in pan on rack.
-
Lift brownie from pan. Cut brownie into 16 squares.