Prepare the Rhubarb Filling:

1. Preheat Conventional oven to 350F, or Convection oven to 335F. Prepare a 13×9 pan by greasing/buttering.  If you would like to lift bars neatly out of the pan, place parchment paper so it overhangs edges of the pan.
2. Into a small or medium saucepan over Medium heat, place rhubarb, berries (if using), sugar, and water.  Heat, stirring regularly, until the fruits exude much of their water and soften, about 8 minutes. 
3. Add the cornstarch, heating and stirring an additional 2 minutes, until the mixture thickens somewhat.
4. Pour into glass or ceramic dish and set aside to cool.

Prepare the Cream Cheese Filling:

1. Whisk together the softened cream cheese, sifted sugar and the egg until smooth. Set aside.

Prepare the Crust/Crumble:

1. Into a medium bowl, add the softened butter, flour, oats, brown sugar, salt, and mix with a spoon or your hands,  until crumbly.
2. Pour half of the mixture into the prepared pan, pressing down with your hands until the bottom of the pan is evenly covered all the way to the corners. Add the sliced almonds to the crumble that remains in the bowl and combine.
3. Pour the cream cheese mixture over the bottom crust and spread within 1/4” of the edges.
4. Pour the mostly cooled rhubarb mixture over the cream cheese, spreading it gently so the layers don’t mix too much.
5. Sprinkle the crumble mixture evenly over the top of the fruit mixture.
6. Place in oven for 28-32 minutes, until golden brown.
7. Cool completely before slicing, especially if you like the bottom crust CRISP!
8. It’s ok to store covered, at room temperature, for a day or two. Otherwise, refrigerate.