Preheat oven to 350°. Line mini muffin pans with paper liners.
Place the butter and 4 ounces white chocolate in a large bowl. Microwave on high in 30 second intervals, stirring between each, until mixture is smooth. It takes my microwave about 90 seconds before I'm happy with the mixture.
Stir in the brown sugar and the white sugar.
Stir in the eggs, one at a time, and beat well after each addition.
Gradually stir in the flour.
Stir in the vanilla.
Then, stir in the white chocolate chips and the nuts.
Just as an aside, don't you love the fact that you don't need to use your mixer for this recipe, just stir, stir and stir.
Spoon the batter into the muffin pans.
Bake for about 15 minutes, until lightly browned.
While the babies are baking, lick your spoon.
Cool in pans for 5 minutes. Then, remove from pans and cool on wire racks.