Position a rack in the middle of the oven. Preheat the oven to 350° F. Line a baking sheet with parchment paper and butter the paper.
In a large bowl, use a fork to stir the coconut, condensed milk, salt, almond extract, and vanilla together. Set aside.
In an impeccably clean medium bowl, use a whisk or a hand-held mixer on low speed to beat the egg white with the cream of tartar until they are foamy and the cream of tartar dissolves. Whisking vigorously or beating on medium-high speed, beat until soft peaks form. Whisk or beat in the sugar. Use a rubber spatula to fold half of the whipped egg white into the coconut mixture, then fold in the remaining white.
Using an ice cream scoop or measuring cup with a ¼-cup capacity, scoop mounds of the coconut batter onto the prepared baking sheet, spacing the macaroons 2 inches apart.
Bake until the bottoms of the cookies and the tips of the coconut shreds are light brown, about 17 minutes. Cool the cookies on the baking sheet for 5 minutes, then slide a metal spatula under the macaroons to loosen them from the parchment and transfer them to a wire rack to cool completely.
Put the chocolate and oil in a heatproof container or the top of a double boiler and place it over, but not touching, a saucepan of barely simmering water (or the bottom of the double boiler). Stir until the chocolate is melted and smooth. Remove from the water and let cool and thicken slightly, about 10 minutes.
Scrape the chocolate coating into a small bowl. Dip the bottom of each macaroon in the chocolate and place the cookies, chocolate bottoms up or on their sides, on a wire rack.(You will have some chocolate coating left over for another use or to pour over ice cream. It’s easier to dip using a larger amount of coating.) Let the macaroons sit at room temperature until the chocolate coating is firm, about 1 hour. Or, to speed the firming of the chocolate, refrigerate the macaroons on the rack for about 15 minutes. Serve cold or at room temperature.