Drain the ricotta: Place ricotta in a fine mesh strainer or cheesecloth over a bowl. Let drain for at least 30 minutes, or overnight if possible, to remove excess moisture.
Make the syrup: In a small saucepan, combine sugar, water, and orange peel. Bring to a gentle boil, stirring until the sugar dissolves. Simmer 5–7 minutes until slightly thickened. Remove from heat, discard peel, and stir in orange blossom water. Set aside to cool.
Prepare the kataif: Gently pull apart the shredded phyllo and pulse it in a food processor in batches to shorten the strands. Place in a large bowl, then pour over melted butter (and saffron water if using). Work the butter into the phyllo with your hands until evenly coated.
Assemble: Butter a round tart pan or baking dish. Press half of the buttered kataif into the bottom in an even layer. Spread mozzarella and drained ricotta on top, then cover with the remaining kataif, pressing firmly to compact everything.
Bake: Bake at 350°F (175°C) for 35–40 minutes, until golden brown and crisp on top.
Finish: Remove from the oven and slowly pour the cooled syrup over the hot kanafe. Let rest at least 10 minutes so the syrup soaks in.
Serve: Garnish with chopped pistachios, optional citrus zest and cut into slices, and serve warm.