Harold McGee, in On Food and Cooking: The Science and Lore of the Kitchen, explains that the "almond" flavor that one expects—and doesn't find in almonds—is benzaldehyde, which is found in bitter almonds and other stone fruits. Unfortunately, the kernels of stone fruits contain both benzaldehyde and cyanide, so they are illegal in the United States—"Our safe 'sweet' almond varieties lack both the bitterness and the characteristic aroma."
I generally make frangipane tarts with almonds and almond extract, but this time I made an apricot-frangipane tart studded with Rainier cherries, and I added two raw apricot kernels (ground up with the almonds and sugar) instead of almond extract (to a three-cup frangipane batch). The apricots were skinned (by blanching) to keep the frangipane from pulling away from the fruit.
The difference was noticable: the tart has a wonderful aroma (it may not be my most beautiful, but the crust was beautifully flaky and it was my most delicious) and the flavor was far superior. I'm not advocating eating apricot kernals in large quanity, certainly, but a couple go a long way. Just wrap the pit in a towel, place on a hard surface (stone, or concrete) and tap with a hammer—voilà: a better frangipane.
