Ducle de leche is a condensed milk, which is cooked. It cooks until it's hardened and turns into a caramel color. Often, we would consume spoonfuls of it at home; our boys especially love eat it over a slice of bread. You should of seen their joy, when they've tasted these cookies.
Sandwich cookies, filled with dulce de leche, are almost like cookies filled with caramel, only 100 times better. Plus, being dipped in chocolate and sprinkled with almonds, they look so luxurious.
With Valentine's Day around the corner, this would be a perfect treat to sneak into your husband's lunch. P.S. Don't forget a cute note, also. :)