In a large bowl, cream together the 1/2 cup butter and sugar until smooth. Blend in the sour cream, 2 tablespoons of milk and eggs. Combine the flour, oats and baking soda, gradually stir into the creamed mixture. Finally, stir in the chopped white chocolate. Drop by rounded spoonfuls onto the prepared cookie sheet. Using a finger or your thumb, press a dent into the center of each cookie. Fill the dent with a 1/2 teaspoon of raspberry preserves.
Bake for 8 to 10 minutes in the preheated oven. Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack to cool completely.
To make the glaze: Combine 1 tablespoon butter and 1/2 ounce white chocolate in a microwave safe bowl. cook on high, stirring every 15 seconds until smooth. Gradually beat in the confectioners' sugar and milk until icing is of a drizzling consistency. Drizzle over cooled cookies.
