Fill the molds with the chocolate and knock them carefully on a hard surface to release any air bubbles. Pour out the excess chocolate back into the bowl of melted chocolate. Scrape the flat portion of the mold to clean off the excess chocolate. Cool the shells to harden completely.
Whip the egg whites to soft peaks. In a small saucepan set over medium heat, cook the sugar to the soft-ball stage, a candy thermometer will read 240 degrees F. Add the hot sugar to the egg whites. Once cool to the touch, add the butter in small chucks. Whip until combined and the mixture becomes soft and creamy. Add the liqueur, then taste and add more if needed. Fill the chocolate shells with the buttercream, then add almonds until the molds are almost completely filled. Top with more melted chocolate, and scrape the excess again, then cool to set up completely.
Release the chocolates from their molds by gently tapping the mold, right-side up, until they all come out. Serve the chocolates at room temperature.