Set a piece of waxed paper or plastic wrap on a plate and break up butter pieces into a single layer. Freeze until solid, 20 to 30 minutes.
In a food processor, pulse together flour, cornmeal, salt, and sugar. Add butter and pulse until chunks are pea-size, 6 to 10 times. While pulsing, drizzle in 1/3 cup ice water and pulse until pastry just starts to come together, about 50 times.
Turn pastry onto a lightly floured work surface, gather together, and knead once or twice until smooth. Form into a 3/4-in.-thick disk, wrap in plastic wrap, and chill until firm, at least 2 hours.
Let pastry disk stand at room temperature until it's just soft enough to roll, about 10 minutes. Unwrap and lightly flour pastry, work surface, and rolling pin. Working from center with short strokes, roll pastry into a 13-in. circle that's an even 1/4 in. thick. As you work, lift pastry using a bench scraper or long metal spatula, and reflour board and pin as needed to keep it from sticking.
Fold pastry in half and open up into a well-buttered regular 9-in. pie pan, easing it into place without stretching. Using scissors, trim overhang to 1 in.
Roll overhang under itself so it's flush with and sitting on top of rim. Pinch pastry along lip to form an even ridge. Flute ridge. Wrap with plastic wrap and freeze until firm, 30 to 40 minutes.
Bake blind: Preheat oven to 400° with a rack in lower third. Line pastry with foil, letting ends come straight up from pan. Fill with pie weights or dried beans. Bake until crust is golden at edges, 25 minutes. Remove foil and weights. If needed, bake until center is dry, about 5 more minutes.
Make ahead: Through step 3, up to 2 days.