Heat your oven to 350°F/175°C and line a 9-inch square baking pan (I used an 8x8") with foil. Give that foil a light coating of vegetable spray.
In a food processor, combine the flour, butter, powdered sugar, and oatmeal. Pulse until combined. Use a spatula to press down any ingredients on the sides of the container. Pulse again until smooth. Reserve about one cup of this mixture and press the rest of it into your prepared pan, being sure to distribute it evenly across the bottom.
Don't bother cleaning out the food processor bowl. Simply add the silken tofu, half cup of sugar, vanilla, lemon zest, and lemon juice into the used food processor bowl. Pulse until combined and smooth. Pour this into the pan over the crust.
In a medium-sized bowl add the frozen blueberries. Sprinkle the sugar and corn starch over the top of the blueberries. Add the lemon juice and gently stir to distribute equally across the blueberries without smashing them. Gently spoon the blueberry mixture over the lemon filling.
Sprinkle dollops of the reserved cup of Crumbly Crust/Topping evenly over the top of the bars.
Place the pan in the oven and bake for 50 to 60 minutes, until the crust becomes a golden brown.
When done, remove the pan from the oven and allow to cool before slicing. I think it's good to wait at least an hour, but you can extend that even longer. It makes for a perfect dish to make the day before a family gathering! When you're ready, simply pull the bars out of the pan by lifting both sides of the foil. This makes clean-up so easy!