Line an 8-inch square baking pan (20 cm) with parchment paper, leaving enough paper overhang to lift out the chilled slab later.
In a large bowl, stir together the vanilla wafer crumbs, 3/4 cup (60 g) shredded coconut, sweetened condensed milk, melted butter, vanilla, and salt until the mixture is evenly moistened and holds together when pressed.
Transfer the crumb mixture to the lined pan. Press it firmly and evenly into the pan, paying attention to the corners. Use the bottom of a measuring cup to compact the base.
Place the chopped chocolate in a heatproof bowl. Warm the heavy cream in a microwave-safe cup just until steaming, about 30 to 45 seconds. Pour it over the chocolate and let stand for 2 minutes.
Stir the chocolate and cream slowly from the center outward until smooth. If needed, microwave the mixture in 10-second bursts, stirring after each burst, until fully melted and smooth.
Spread the chocolate topping evenly over the base. Immediately scatter the remaining 1/2 cup (40 g) shredded coconut over the top and lightly press it into the chocolate.
Refrigerate until the topping is firm and the bars are easy to slice, at least 2 hours. Lift out using the parchment overhang, warm a sharp knife under hot water and dry it, then cut into 16 squares. Keep chilled until serving.