In a saucepan over high heat, combine the sugar, water, corn syrup, cinnamon stick, cloves, and the halved orange. Bring to a boil, stirring until the sugar dissolves and the mixture becomes clear. Remove from heat and let cool completely.

In a food processor, pulse the walnuts, cinnamon, breadcrumbs, and cloves in batches until finely chopped but not powdered. Transfer the mixture to a bowl and stir with a spoon. This is your baklava filling.

Preheat the oven to 300°F (150°C) with convection if available. Generously butter a baking pan using a pastry brush.

Place the pan with its long side facing you. Start layering the phyllo sheets to form the base. Carefully lay the first sheet of phyllo so the long side covers about two-thirds of the pan, letting the edges hang over the sides. Gently press the sheet into the corners of the pan with your hand.

Repeat with the second sheet, this time from the opposite side, slightly overlapping the first. Drizzle melted butter over the sheets, making sure not to touch the phyllo with the brush. Then, lay the third sheet across the entire surface of the pan, pressing it into the corners as before. Butter as before.

Spread a handful of the nut filling evenly over the pan. Lay another sheet of phyllo with its short side against the top long side of the pan. Butter as before. Spread another handful of filling evenly. Add another sheet, butter, and filling, repeating the process.

Continue layering filling, phyllo, and butter, alternating, until you have used all the filling, reserving 3 sheets for the top. Fold the overhanging edges of the phyllo into the pan and press down gently. Add 2 more sheets on top, buttering each one. Place the final sheet on top, folding and pressing the edges in with the brush. Pour the remaining melted butter over the top.