In a food processor, pulse the walnuts until it forms fine crumbs, then transfer to a bowl and mix with honey and cinnamon until evenly combined.
Cut the phyllo sheets to the same size as an 8x8 inch pan. Lightly grease the base of the 8x8 inch pan with melted butter, then add one phyllo sheet at a time, brushing each with melted butter before adding the next sheet. Keep the phyllo dough you aren't working with covered with a damp towel or it'll quickly start to dry out and crumble.
Keep going until you have 12 phyllo sheets stacked on the base of the pan. Add all the walnut filling, and spread it out evenly. Top with the thinly sliced apples
Add all the walnut filling, and spread it out evenly. Top with the thinly sliced apples.
Add another sheet of filo dough on top, brush with melted butter and repeat this process with another 12 sheets of filo dough, buttering each.
Use a sharp knife to cut diagonals into the baklava, and pour any remaining melted butter over the top.
Bake for 20 minutes, then reduce heat to 160C, and bake another 35-40 minutes until golden brown all over.
Remove from the oven and pour the syrup evenly all over the hot baklava. Let the pan sit until cooled and syrup is absorbed, at least an hour. Enjoy!