When I refer to this pie as "delicate," it is strictly because there are purists and there are.....well, purists! Many swear by graham cracker crust while others will fight for the pastry crust. Many purists believe that you should never substitute the 4 egg yolks, regardless of the health benefits substituting as I have below. There is one concession, though, that all Key Lime aficionados agree on. Do not ever use green food coloring. True Key Lime Pie should be an almost pale yellow in color. As for the limes, if you see that key limes are just simply too expensive, substitute regular limes. They are less acidic, and the taste will be just a tad less intense, but you will get the great citrus flavor none-the-less.
Authentic Key Lime Pie 9 inch prepared graham cracker pie crust 15-ounce can of sweetened condensed milk 4 egg yolks 1/2 cup key lime juice 3 to 4 teaspoons grated lime zest, optional*
Preheat oven to 325-degrees F. In a medium bowl, with a hand-held or tabletop mixer, beat the egg yolks on high until creamy, about 30 seconds. Add the sweetened condensed milk, lime juice and lime zest. Reduce the speed on your mixer to low and beat until just incorporated, about 1 minute.
Pour the filling into the graham cracker crust and bake for about 16-18 minutes, or until the center is set but the edges are still slightly wobbly. Remove from oven, let stand on counter for 30 minutes and then cover with film wrap to finish chilling completely in refrigerator. Enjoy with either whipped cream or guess what? There are still more people that say Key Lime Pie should have meringue as a topping. Of course, if you were to take that route, you would have to beat your meringue with sugar, spread it on top of the chilled pie as you would whipped cream. Many don't like the idea of eating raw egg product, but that would be entirely up to you. Mix it half-and-half with whipped cream if that makes you feel better.
* I don't add zest to my recipe. I think it gives this great pie too much of an off-taste, but if you are a stickler as well with regards to an authentic Key Lime Pie, please....no emails, just add it.