Preheat your oven to 350 degrees F.
In a large bowl, toss together the rhubarb and ginger.
Transfer the mixture into a 2 or 3 quart baking dish and sprinkle 2 cups of the sugar over top; set aside.
In a medium bowl, whisk together the flour, remaining sugar, and salt.
Add the butter and cut it into the flour mixture until it resembles coarse meal.
Sprinkle the crumble topping evenly over the rhubarb mixture.
Bake for about 1 hour and 15 minutes, or until the topping is golden brown and the rhubarb mixture is bubbling.
Cool slightly on a wire rack and serve warm or at room temperature.
Top with ice cream or fresh whipped cream if desired.
