1. Preheat the oven to 400 degrees F
2. Pulse the walnuts in a food processor
3. Grease a baking pan with butter and layer with 6 to 8 phyllo sheets. Brush with butter in between layers.
4. Sprinkle with crushed walnuts
5. Put another layer of phyllo, layering with butter in between layers.
6. Carefully slice the baklava into 1 ½-inch-wide strips lengthwise, then slice diagonally to create diamond-shaped baklava. Or just slice squares if you prefer.
7. Bake the baklava for 50 minutes, until golden on the edges and tops
8. Let the baklava cool for 5 to 6 hours before serving