
Mix cornstarch and lemon juice in a small bowl. Warm blueberries and sugar in a saucepan for 3 minutes. Stir in cornstarch mixture, cooking for 2 more minutes. Remove from heat and set aside.
Preheat oven to 350°F (177°C).
Combine melted butter, sugar, vanilla extract, and salt. Stir in flour to create dough. Press into a 9-inch tart pan and bake for 15 minutes.
Poke holes in the warm crust, whisk filling ingredients, and pour into crust. Swirl blueberry sauce on top and bake for 17-19 minutes.
Cool completely, chill for 2 hours, serving with garnishes.
Cover leftovers and refrigerate for up to 1 week.