Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking dish and set aside.

In a medium saucepan, combine the chopped rhubarb, granulated sugar, and water. Cook over medium heat until the rhubarb softens, about 5-7 minutes.

Remove the saucepan from heat and stir in the strawberry Jello powder until fully dissolved. Set the mixture aside to cool slightly.

In a mixing bowl, combine the flour, rolled oats, brown sugar, melted butter, and a pinch of salt. Stir until the mixture becomes crumbly.

Press half of the crumb mixture evenly into the bottom of the prepared baking dish to form the crust.

Pour the rhubarb and Jello mixture over the crust, spreading it out evenly.

Sprinkle the remaining crumb mixture on top of the rhubarb filling to create the topping.

Bake in the preheated oven for 35-40 minutes, or until the topping is golden brown and the filling is bubbling.

Remove from the oven and let the dessert cool completely before serving. Optionally, serve with whipped cream or vanilla ice cream.