For cookies, beat butter, confectioners’ sugar and vanilla in large bowl with electric mixer until creamy. Add combined flour, walnuts and salt; beat just until combined. Add oats; beat just until combined. Cover and refrigerate dough until firm, about 2 hours or over night. For filling, combine cranberries, granulated sugar and water in small heavy sauce pan. Bring to a boil; reduce heat simmer gently, stirring frequently, until cranberries pop and mixture thickens. Cool slightly. Cover and refrigerate until ready to use. Heat oven to 350°F. pinch off pieces of dough and roll into 1-inch balls. Place 2-inches apart on ungreased cookie sheets. Use thumb to make deep indentation in center of each ball. Bake 10 to 12 minutes or until bottoms are light golden brown. Cool 2 minutes on cookie sheets. Transfer to wire racks; cool completely. Store cooled cookies at room temperature in airtight container, separating layers with parchment or waxed paper, up to 3 days or freeze up to 3 months. Thaw in container at room temperature. To serve, fill centers of each cookie with 1/2 teaspoon cranberry filling. Melt chocolate according to package directions. Transfer to resealable plastic sandwich bag and seal. Snip tiny piece from corner of bag. Pipe chocolate over each cookie. Refrigerate just until chocolate sets.