Preheat oven to 325 degrees F. or 300 degrees convection. Line two baking sheets with parchment paper.
Mix sweetened condensed milk and vanilla extract in a large bowl. Add coconut and stir until combined. Beat egg-whites, salt and cream of tartar in another clean mixing bowl with electric beater on high until soft peaks form. Fold egg-whites in two batches into the coconut mixture to lighten. Stir in 1 cup apricots.
Measure out 1 level tablespoon of coconut mixture and drop onto the parchment. Top that dollop with another even tablespoonful. Continue with the remaining coconut mixture, spacing evenly between the two pans. Bake, rotating half way, until the tops are turning golden, 22 to 25 minutes. Let cool completely.
Bring 1 to 2 inches of water to a simmer in the bottom of a double boiler. Reduce heat to maintain the barest simmer. Make an ice bath in a large bowl. Set up a towel next to the ice bath to dry off the bottom of the bowl and to keep it from skidding around.
Place the chocolate in cool, clean, dry top of the double boiler. Place over the simmering water and stir until the chocolate is almost completely melted, allowing steam to evaporate as necessary, about 3 minutes. Remove from the heat and continue stirring until the chocolate is completely smooth
Place the bowl of melted chocolate over the ice bath and stir until there is a thin layer of solid chocolate at the bottom of the bowl. Make sure not to splash any water into the chocolate. Transfer the bowl to the prepared towel and stir until the chocolate is melted off the bottom. Return the bowl to the ice bath and stir until a solid layer is formed again. Repeat stirring the chocolate on the towel. Continue this process until the chocolate will no longer melt when it is moved to the towel, it becomes matte and thick.
Working quickly, transfer the bowl to the double boiler and stir until the chocolate starts to soften and become glossy around the edges 5 to 15 seconds. Remove to the towel and stir until the chocolate is evenly melted.
Transfer tempered chocolate to pastry bag, parchment cone, or small re-sealable plastic bag. (Cut small tip off parchment or plastic bag if using.) Squeeze chocolate out in a thin ribbon and carefully swirl chocolate over all of the macaroons. Top macaroons with the remaining ¼ cup apricots before the chocolate sets-up. Slide a thin flexible spatula under each macaroon to remove it from the parchment and transfer to a platter to serve.