On a large baking sheet, add the oats and almonds. Toss to combine and spread out evenly. Bake for 10-15 minutes until toasted. Remove and let cool completely to room temperature.
Transfer the cooled, toasted oats and almonds to a large mixing bowl. Add almond butter, honey, and melted butter. Use a spatula to mix until combined.
Fold in the chocolate chips and freeze-dried berries (if using).
Line a baking sheet with parchment paper and allow for an overhang on two sides. Add the granola mixture and spread it across the bottom. Use a spatula or the back of a flat-bottomed measuring cup to pack in very tightly and evenly.
Transfer the pan to the fridge and chill until set, about 30 minutes. Once hardened, carefully remove the large granola square using the parchment paper overhang. Use a sharp knife to slice horizontally.
Optional: drizzle the melted chocolate over the granola bars. Place back in the fridge until the chocolate is completely hardened.