FOR THE STREUSEL: Adjust oven rack to upper-middle position and heat oven to 425 degrees. Process flour, granulated sugar, brown sugar, butter, and salt in food processor until mixture resembles coarse sand, 4 to 5 pulses. Add pecans and process until pecans are coarsely chopped, about 4 pulses. Transfer to small bowl; set aside.
FOR THE MUFFINS: Spray 12-cup muffin tin with baking spray with flour. Whisk flour, baking powder, ¾ teaspoon salt together in bowl; set aside.
Process toasted pecans and granulated sugar until mixture resembles coarse sand, 10 to 15 seconds. Transfer to large bowl and whisk in eggs, butter, and milk until combined. Whisk flour mixture into egg mixture until just moistened and no streaks of flour remain. Set batter aside 30 minutes to thicken.
Pulse cranberries, remaining ¼ teaspoon salt, and confectioners’ sugar in food processor until very coarsely chopped, 4 to 5 pulses. Using rubber spatula, fold cranberries into batter. Use ice cream scoop or large spoon to divide batter equally among prepared muffin cups, slightly mounding in middle. Evenly sprinkle streusel topping over muffins, gently pressing into batter to adhere. Bake until muffin tops are golden and just firm, 17 to 18 minutes, rotating muffin tin from front to back halfway through baking time. Cool muffins in muffin tin on wire rack, 10 minutes. Remove muffins from tin and cool for at least 10 minutes before serving.