This recipe has four components. I used a couple of shortcuts because I was pressed for time. First you need a tart crust. I substituted a store bought pie crust. Next there is the lemon - almond cream. This is a simple mixture of butter, brown sugar, almond flour, lemon zest, and egg. Then there is the grapefruit cremeux, a wonderful cooked custard. I left out the Campari and wasn't able to think of a good non alcoholic substitute in the short time I devoted to this project. Finally you top the tart with grapefruit segments. I used jarred fruit brought to me by the family's shopper.
The lemon - almond cream and the grapefruit cremeux both require chilling, as does the completely assembled tart. If I make this again I will map out the time needed for all the parts before I start, working backwards from the time I want to serve the tart.
It tastes pretty good, and would be even better with a home made crust and an additional flavoring in the cremeux.