• ​Preheat oven to 350 degrees with the oven rack in the middle position. 
• Lightly grease a 9 x 13 or 9 - inch round baking dish. 
• Cream the butter with the brown sugar in a medium bowl. Mix in the flour, old-fashioned oats, and salt until fully combined.
• Remove rhubarb leaves and root ends and discard. Wash the fresh rhubarb stalks to remove any dirt and cut them into 1-inch pieces until you have 8 cups of rhubarb.
• Mix rhubarb pieces, brown sugar, all-purpose flour, vanilla extract, and a pinch of salt in a large bowl. 
• Pour the tart rhubarb mixture into the prepared baking dish and spread evenly. 
• With clean hands, sprinkle the crumble mixture evenly over the rhubarb.
• Place in the oven and bake for 55 - 60 minutes. The rhubarb will be soft and bubbly while the crisp topping will be a light golden brown. 
• Serve warm with a big scoop of vanilla ice cream or homemade whipped topping.

Storage Instructions

• Rhubarb crisp is at its best the same day it's baked.  Store rhubarb crisp in an airtight container or cover the baking dish with plastic wrap and keep in the refrigerator for 3 days. Rhubarb crisp can be kept at room temperature for up to 24 hours. The crisp topping will soften with time.