Preheat oven to 350°F (175°C). Prepare a 9x13 inch baking pan.
Combine flour, brown sugar, and salt. Cut in cold butter until mixture resembles coarse crumbs.
Press the crumb mixture into the prepared pan.
In a saucepan, combine cranberries, sugar, brown sugar and melted butter. Bring to a boil, then reduce heat and simmer until cranberries burst and mixture thickens.