Heat butter, sugar and water in saucepan until butter is melted. Remove from heat and add chocolate chips and stir until melted. Pour into large bowl and cool 10 minutes. Beat in eggs, then add flour, soda and salt and beat just until blended. Chill dough for an hour. Don't worry that the dough seems a little bit oily - it turns out fine once baked. Line cookie sheets with foil. Roll dough in 1" balls and place 2" apart on cookie sheets. Bake at 350 degrees Fahrenheit for about 11 minutes. Remove from oven and immediately place an Andes mint on each cookie. After they melt, swirl each one with a knife (think of it like spreading frosting on a cake but with the Andes mint instead) and remove cookies from cookie sheet and let them cool until chocolate is solid.