In a food processor, combine flour and salt; pulse to mix. Add cold cubed butter and pulse until mixture looks like coarse crumbs with pea-sized butter pieces. Add ice water one tablespoon at a time, pulsing just until dough clumps together.
Turn dough out onto a floured surface and divide into two equal portions. Shape each into a flat disk, wrap in plastic, and refrigerate for at least 1 hour.
Roll one disk into a 12-inch circle on a floured surface. Transfer to a 9-inch pie dish, pressing into the bottom and up the sides. Trim overhang to 1 inch past the rim and chill while making filling.
In a large bowl, gently combine raspberries, 3/4 cup sugar, cornstarch, lemon juice, lemon zest, cinnamon, and salt. Fold carefully to keep berries whole. Let rest for 10 minutes.
Roll the second dough disk into a 12-inch circle. For a lattice top, slice into strips; for a solid top, leave whole and set aside on parchment.
Preheat oven to 425°F. Pour filling into chilled bottom crust and dot with butter pieces. Place top crust over filling, trim excess, fold edges under, and crimp to seal. Cut slits in a solid top crust to vent.
Brush top crust with beaten egg wash and sprinkle with coarse sugar if using. Cover edges with a pie crust shield or foil. Bake at 425°F for 20 minutes, then reduce to 375°F and bake 30-35 minutes more until golden and bubbling.
Transfer to a wire rack and cool for at least 3 hours before slicing to allow filling to set.