Preheat your oven to 350. Grease an 8" metal or glass pan.
Using electric mixer, mix butter and 1 cup brown sugar until fluffy. Add eggs one at a time, beating well after each one.
In a seperate bowl mix flour, baking soda, baking powder and salt. Alternate adding the flour mixture and buttermilk to the butter/brown sugar mixture by: add 1/3 flour mixture and half the buttermilk, 1/3 flour mixture, rest of the buttermilk and then the rest of the flour mixture. You will probably need to stir the last of the flour mixture in.
Stir in cranberries and 3/4 cup white chocolate chips. Pour into pan and smooth out batter. Sprinkle 1/2 cup brown sugar and remaining 1/4 cup white chocolate chips over top of batter.
Bake for 1 hr. Check for doneness, mine usually only takes an hour but ovens vary.