Line an 8 x 8” baking pan with parchment paper so it hangs over 2 opposite sides. Preheat oven to 350°F.
To make crust: In a food processor, combine sugar, flour, cinnamon, salt, and butter. Process until it comes together and will clump when squeezed. Set aside ¾ of mixture. Dump the remaining mixture in prepared pan and press evenly along bottom. Set aside.
To make filling: Whisk together egg, sour cream, sugar, lemon juice, flour, cornstarch, vanilla, and cinnamon in a medium bowl until smooth. Whisk in 1 cup of blueberries.
Pour filling evenly over prepared crust, giving the pan a gentle shake to disperse evenly. Spread remaining 1 cup blueberries evenly over top. Take the set aside, unused crust and sprinkle over top with hands, encouraging large lumps.
Bake for 1 hour. Let cool and cut into 9 pieces evenly. Refrigerate until ready to serve.