First, make the raspberry chia jam filling. Place the raspberries, maple syrup, and lemon juice into a small saucepan and place over medium heat. Bring the mixture to a simmer, then lower the heat and allow to simmer until the berries begin to soften, about 5 minutes. Mash the berries with the back of a spoon and stir in the chia seeds. Continue simmering for about 10 minutes, stirring occasionally.

Remove the saucepan from the heat and allow to sit while you prepare the base/crumble topping. The jam will continue to thicken as it cools.

Preheat the oven to 350°. Lightly oil the bottom of a 9 x 9 inch square baking pan.

In a large mixing bowl, stir together all of the ingredients for the base/crumble topping, until everything is uniformly blended. Dig in with your hands if you need to.

Place about ⅔ of the base/crumble topping mixture into the bottom of the prepared baking pan to create the base. Press very firmly to uniformly coat the bottom of the pan. Spread the chia jam over the base, then crumble the remaining base/crumble topping mixture over the jam.

Bake for about 30 minutes, until the crumble topping begins to brown.

Remove from the oven and transfer the pan to a cooling rack. Allow to cool completely before cutting into squares.