Step 1

Begin by making the filling. Over medium heat, bring the rhubarb, raspberries, and sugar to a boil. Let the mixture cook until mostly all the rhubarb has lost it's shape, about 15 minutes.

Step 2

Take the fruit mixture off the heat and stir in the orange zest, vanilla, and chia seeds.

Step 3

While the filling is cooling (about 15 minutes), preheat the oven to 350 degrees Fahrenheit and line a 9 x 9 inch pan with parchment paper.

Step 4

Mix together the flour, oats, brown sugar, and salt in a medium sized mixing bowl.

Step 5

Add the melted butter to the flour and oat mixture and mix well.

Step 6

Take 2/3 of the crumble and press it down into the prepared pan. Then spread the fruit mixture on top. Finally, place the remaining crumble on top of the filling.

Step 7

Bake in the oven for 55 minutes. Let cool completely (yes, I am talking a few hours) on a wire rack before cutting into slices.