Preheat oven to 250º.
Line a large baking sheet with parchment paper, and secure with masking tape.
Place unsweetened chocolate in a small microwave-safe bowl. Microwave at high for 1 minute or until almost melted. Remove from microwave; stir until chocolate is completely melted.
Spoon flour into a dry measuring cup; level with a knife. Combine cake flour, unsweetened cocoa, and salt in a large bowl. Add coconut, and toss well. Stir in melted chocolate, vanilla extract, and sweetened condensed milk (the mixture will be stiff). Drop by level tablespoons 2 inches apart onto prepared baking sheet. Bake at 250º for 45 minutes or until edges of cookies are firm and center of cookies are soft, rotating baking sheet once during baking time. Remove from oven, and cool 10 minutes on pan on a wire rack. Remove the cookies from the parchment paper, and cool completely on rack. Store in an airtight container.