Line your baking dish with parchment paper, leaving overhang on the sides for easy lifting later.
In a large mixing bowl, combine the oats and chopped nuts, stirring to distribute evenly.
In a small saucepan, gently heat the honey and peanut butter over low heat, stirring constantly until smooth and slightly runny, about 2 minutes. The mixture should be glossy and fragrant.
Pour the warm honey-peanut mixture over the oats and nuts, using a spatula to fold and coat everything thoroughly. The mixture should become sticky and glossy, with oats starting to clump together.
Transfer the mixture into your prepared baking dish, pressing it firmly with the back of a spatula or your hands to create an even, compact layer. This helps the squares hold together nicely.
Once evenly pressed, smooth out the top surface. Place the dish in the fridge and chill for at least 2 hours or overnight until the mixture is firm and set.
After chilling, lift the set mixture out of the dish using the parchment overhang, then place on a cutting board.
Using a sharp knife, cut into 12 even squares. Wipe the knife between cuts for clean edges.
Serve the squares immediately or store in an airtight container at room temperature for up to 2 days, or refrigerated for longer freshness.
