Chewy Chocolate Molasses Cookies

Adjust oven racks to upper-middle and lower-middle positions and preheat oven to 375°F. Line two large baking sheets with parchment paper. In a large bowl, cream butter with brown sugar, 1/2 cup granulated sugar, and salt until combined. Whisk in egg, vanilla, and molasses. In a medium bowl, whisk flour with cocoa and baking soda until evenly distributed. Whisk dry ingredients into wet mixture until just combined. Chill dough until firm, about 20 minutes. Place remaining 1/2 cup sugar in small bowl. Using a cookie scoop or 1/4 cup measure, portion dough into balls, and roll in sugar. Space evenly on pans and gently press dough balls to about 3/4 inch thick. Bake just until puffed and beginning to crack, about 8 minutes, rotating pans from top to bottom and front to back halfway through baking. The cracking will be obvious. Don't worry about missing it. Immediately after removing from oven, give pans a hard tap on the bottom and gently press each cookie with a spatula or other flat object. Let cookies cool on pan 2 minutes, then transfer to wire rack to cool completely.