Adjust oven racks to upper-middle and lower-middle positions and heat oven to 350°F. Line two cookie sheets with parchment paper.
Whisk together cream of coconut, corn syrup, egg whites, vanilla, and salt in small bowl; set aside. Combine unsweetened and sweetened coconuts in large bowl; toss together, breaking up clumps with fingertips. Pour liquid ingredients into coconut and mix with rubber spatula until evenly moistened. Chill dough for 15 minutes.
Scoop dough using a one ounce (2 tablespoon) size cookie scoop, spacing them about 1 inch apart on parchment lined baking sheet. Form cookies into loose haystacks with fingertips, moistening hands with water as necessary to prevent sticking. Bake until light golden brown, about 18-20 minutes, turning cookie sheets from front to back and switching from top to bottom racks halfway. Cool cookies on cookie sheets, set over wire cooling racks.
Line two cookie sheets with parchment paper. Melt about 3/4 of the chocolate (212 grams) in small heatproof bowl set over pan of almost-simmering water, stirring once or twice, until smooth. (To melt chocolate in microwave, heat at 50 percent power for 2 minutes and stir. If chocolate is not yet entirely melted, heat an additional 30 seconds at 50 percent power.) Remove from heat; stir in remaining 1/4 of the chocolate (71 grams) until smooth. Holding macaroon by pointed top, dip bottom and ½ inch up sides of each cookie in chocolate, scrape off excess with finger, and place on cookie sheet. Refrigerate until chocolate sets, about 15 minutes.