Preheat the oven to 350°F/180°C and line an 8x8 square pan with parchment paper. Set the pan aside.
Spread the almonds and cashews on a baking sheet and toast until just barely golden brown and fragrant. Remove from the oven and allow to cool slightly before chopping roughly into 2/3 inch / 1.5 cm pieces and placing the pieces in a large mixing bowl.
In the bowl of a food processor, pulse 3/4 cup / 80 g of the oats into small pieces. Be careful not to turn the oats into powder, though! These processed oats will help hold the bars together. Combine them with the nuts and the remaining unprocessed oats in the large mixing bowl.
Add all of the seeds to a small frying pan and toast gently over medium heat on the stove until just barely brown and very fragrant. Add these toasted seeds to the nut and oat mix, along with the chopped dates. Mix to combine and then set aside.
Now, return to the browned butter, still in liquid state. If your brown butter has cooled and is now solid, rewarm it over low heat until liquid again. Add the sugar, corn syrup and orange zest. Remove from the heat and add the orange blossom water, cinnamon and salt and stir to combine. Then, pour over the oat mixture. Mix well, then tip the mixture out into the prepared pan.
Use a small spatula or the back of a spoon to smooth the granola bars evenly into the pan, making sure to fill the corners.
Bake the bars for about 35 minutes, or until they're bubbling and have a nice dark golden color. Remove them from the oven and allow to cool in the pan for 30 minutes or so before cutting into squares or rectangles. (If you remove them from the pan, they'll fall apart!) No matter what shape you choose, you want to cut them before they harden and cool completely. Store in an airtight container and enjoy at will.