Preheat oven to 400°F. Line a 9-inch square baking pan with parchment paper.
In a saucepan, cook the raspberries, maple syrup, and vanilla over medium heat. When the mixture begins to cook down and thicken, stir in the chia seeds. Take the mixture off the heat and set aside to thicken.
In a food processor, blend the oats, walnuts, and dates until a crumbly and slightly moist mixture forms. Add the applesauce, water, cinnamon, baking soda, and salt. Pulse until a thick, crumbly dough forms.
Firmly press half the oatmeal mixture into the prepared pan. Use a spatula to spread the thickened raspberry mixture evenly over the crumble mixture. Top with the remaining oat mixture and press lightly.
Bake until golden brown, 25-30 minutes. Cool thoroughly and cut into bars.