Put the silicone mold on a baking sheet. Melt the chocolate in a completely dry heatproof bowl over gently simmering water, or use microwave bursts of about 20 to 30 seconds, stirring between bursts. Keep water, steam, and wet utensils away from the chocolate because even a small amount can make it seize.
For a simple untempered shell, melt the chocolate gently until smooth. For a more glossy, firm shell, use a basic tempering route: melt about two-thirds of the chocolate, remove it from the heat, and stir in the remaining one-third until smooth and slightly cooled. Milk chocolate is worked at a lower temperature than dark chocolate, so a thermometer is useful if you have one, although it is not required for this home recipe.
Spoon enough chocolate into each mold to cover the bottom and all sides. Rotate or spread the chocolate up the walls, then tip out excess chocolate and scrape the rim clean. The coating must be continuous, with no thin gaps or exposed silicone. Chill the coated molds for about 5 to 10 minutes, until the shell is firm.
A shell should be thick enough to hold the filling but not so thick that it overwhelms the kataifi crunch. Untempered melted chocolate can still produce a tasty bar, but it may be softer, less glossy, and more prone to melting at room temperature. If the chocolate is still very warm, wait briefly before adding a decorative white or green layer so the decoration does not blur.