Preheat the oven to 350 degrees F (175 degrees C).

Combine condensed milk, almond extract, vanilla extract, salt, and egg white in a bowl. Whisk until thoroughly combined. Add about 2 1/3 cups shredded coconut. Mix with a spatula until mixture is sticky and holds together. Form into balls using a sorbet scoop.

Roll balls in remaining coconut. Space macaroons evenly onto a silicone-lined baking sheet.

Bake in the preheated oven until golden, about 20 minutes. Let cool to room temperature, at least 20 minutes.

Meanwhile, place 3/4 of the chocolate in top of a double boiler over simmering water. Stir frequently, scraping down the sides with a rubber spatula to avoid scorching, until chocolate is melted, about 5 minutes. Remove from heat and stir in the rest of the chocolate until it melts.

Dip the base of each cooled macaroon about 1/8 inch into the chocolate. Place cookies, chocolate-side down, on parchment paper. Let chocolate harden completely.