In a small bowl - mix flour, oats and brown sugar. Cut butter into small cubes and using a pastry cutter make a course crumble out of the butter and dry mixture.
Reserve 1 cup of the crumble mixture for the top and press the remaining crumble mixture into the bottom of a 9 inch square baking dish that has been sprayed with non-stick spray.
In a bowl using electric mixer beat cream cheese, sugar, and salt until smooth. Add the egg and the vanilla beat on low speed until combined and smooth. Spread over the crust.
In a small bowl place the diced rhubarb and strawberry topping - stir to combine and coat the rhubarb. Carefully pour the strawberry coated rhubarb over the cheesecake layer.
Sprinkle the reserved cup of crumble mixture over the rhubarb layer.
Bake in a 350° pre-heated oven for 40-45 minutes until golden brown and cheesecake layer is mostly set. It will be set around the edges and just slightly jiggly in the middle but will set up as it cools......if your family can wait!