Blueberry-Buttermilk Pie Bars from Dorie's Cookies are an easy to make two layer square.
The crust is unusual in that it has cornmeal and cornstarch in addition to the usual butter, sugar, and flour. The topping is a custard made with buttermilk, eggs, butter, and sugar, plus blueberries.
The people I shared this treat with wondered if it was cheesecake. It tastes great and is something I will plan to bake again.