1. Preheat the oven to 325°F. Line two baking sheets with parchment paper.
2. In a large bowl, stir together the sweetened condensed milk, lime juice, lime zest, egg white, vanilla extract, and salt. Stir until combined. Add in the coconut and mix well.
3. With a spoon, scoop up about 2 Tablespoons of the coconut mixture and form into mounds that have a slight peak at the top. Place on lined baking sheets, about two inches apart. Bake cookies one sheet at a time for 15 to 20 minutes, or until cookies are set and slightly golden brown.
4. Cool the cookies on the baking sheets for about 5 minutes. Remove with a spatula onto a cooling rack.
5. Melt chocolate in a microwave safe bowl. Make sure you keep stirring the chocolate every 20 seconds or so until chocolate is melted and smooth.
6. Lay out a large piece of wax paper. Dip the cookies into the chocolate-just so the bottoms are covered in chocolate. Set dipped cookies on the paper to dry. Drizzle macaroons with white chocolate and let dry completely.