In a large bowl, combine 2 cups flour, 1/2 cup white sugar, brown sugar, baking powder and salt. Stir in milk, egg, melted butter and lemon peel. Fold in 1 1/2 cups white chocolate chips and blueberries. Spoon into prepared muffin cups, filling almost full. In a small bowl, mix together 1/3 cup white sugar, 1/4 cup flour and cinnamon. Cut in 3 tablespoons butter or margarine with pastry blender or two knives until mixture resembles coarse crumbs. Sprinkle unbaked muffins with topping.

Bake in preheated oven for 22 to 25 minutes or until a toothpick inserted into center of a muffin comes out clean. Cool in pans for 5 minutes then remove to wire racks.

Melt remaining 1/2 cup of white chocolate chips over a double boiler or in the microwave. Place into a small but strong plastic bag, cut one tiny corner off. Squeeze bag to drizzle over muffins. Serve warm.