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mix
shortbread: butter + 2 cups flour + 1/2 cup powdered sugar + salt to damp crumbs, pressed into a lined 9x13
cold butter worked into the dry goods until the mix holds when squeezed — the pie-crust chapter's rubbing motion with a lazier standard — then pressed flat and even into the parchment-lined pan; even is the discipline: thin corners overbake first