Many of us bakers have a few go-to recipes that satisfy every time. Maybe that’s a batch of fudgy brownies, a pan of cookie brittle or a loaf of banana bread. Classics like these always hit the spot.

At this point, magic cookie bars (also known as “seven-layer bars” or “Hello Dolly bars”) should be declared obligatory for any event where a dessert table is involved. They’re a guaranteed to please ...