Place the chopped dark chocolate in a microwave-safe bowl. Microwave in 30-second bursts, stirring between each, until the chocolate is smooth and glossy.
Add honey and butter to the melted chocolate. Stir well until the mixture is shiny and fully combined, creating a rich, smooth sauce.
Stir in the vanilla extract if using, to deepen the flavor, and mix until evenly incorporated.
Add the rolled oats and toasted nuts to the chocolate mixture. Fold gently with the spatula until everything is well coated and sticky, creating a thick, textured dough.
Line your baking dish with parchment paper, leaving some overhang for easy removal. Pour the mixture into the dish and press down firmly with the back of a spatula, smoothing the surface as evenly as possible.
Sprinkle a pinch of sea salt on top if desired, for a touch of contrast. Cover the dish with plastic wrap or foil and place it in the fridge.
Chill in the refrigerator for at least 2 hours, or until the bars are firm and glossy on top.
Once set, lift the bars out of the dish using the parchment overhang. Use a sharp knife to cut into even squares or rectangles.
Serve immediately for a chewy, gooey treat, or store in an airtight container in the fridge for up to a week. Enjoy these rich, velvety bars whenever craving hits.
