While the crust bakes, combine the filling ingredients until everything is smooth. (super-hard, this step.....)
When the crust comes out of the oven, pour the filling misxure into the hot crust, then pop it back in the oven until it sets ... somewhere around 15 minutes, but start checking early.
If the crust is getting too brown before the filling is set, you can make a little shield of aluminum foil and gently wrap the crust edges with it. (I clearly did not do that, hence the tip. 🤗)
When it's done, cool the bars to room temperature on a rack, then cut them into 16 squares. (4x4 is easy and creates loads of yummy edge pieces that can be picked up and eaten over the kitchen sink not that I'd ever do that, right? but again, you do you.)
Dust them with powdered sugar for that extra little touch of class.
If somehow you manage to have some leftover, keep them in the fridge, covered with saran wrap. They'll keep a few days, although I can't say i've ever had them last long enough to know how long.