Tear croissants into small pieces and place in a large bowl. Add sugar and cinnamon. Mix milk, eggs and vanilla. Mix well. Let bread soak up with mixture while your oven preheats.
Preheat oven to 350 degrees F. Butter prepared pan. Pour croissant mixture into pan and bake for 45 to 50 minutes, or until center is set.
Add all ingredients to a small saucepan and boil for one minute. Mixture will foam up. As it cools, the foam will disappear. Add chopped pecans to the sauce if desired. Serve warm.