Preheat oven to 375 degrees.
Melt butter in medium saucepan over low heat. Remove from heat. Stir in oats, sugar, flour, corn syrup, milk, vanilla, and salt. Mix well.
Drop by level teaspoonfuls about 3 inches apart onto foil lined cookie sheets. Spread thin with rubber spatula.
Bake for 5-7 minutes. Cool completely. Peel foil away from cookies.
Melt milk chocolate chips over hot (not boiling) water, stirring until smooth.
Spread chocolate on flat side of half of the cookies. Top with remaining cookies.