Line a baking sheet with parchment paper or a silicone mat. Set aside in a cool area of your kitchen.
Chop the dark chocolate into uniform pieces for even melting. Place in a heatproof bowl.
Melt the chocolate using a double boiler or microwave in 30-second intervals, stirring between each, until smooth and completely melted. Do not overheat.
Pour the melted chocolate onto the prepared baking sheet and spread into an even layer about 1/4-inch thick using an offset spatula.
Tap the baking sheet firmly on the counter 2-3 times to release any air bubbles and smooth the surface.
Immediately sprinkle the chopped almonds evenly over the chocolate, pressing them gently into the surface.
Finish with an even sprinkle of flaky sea salt across the entire surface while the chocolate is still wet.
Refrigerate for 15-20 minutes until completely firm and set. The chocolate should snap cleanly when broken.
Remove from the refrigerator and break into irregular pieces by hand, or cut into neat rectangles with a sharp knife. Store in an airtight container with parchment between layers.
