Preheat the oven to 350˚F. Butter or spray your tart pans with a light coat, then set aside.
Crumb graham crackers in a food processor until fine. Run your fingers through and either break or remove any larger pieces, as these can sometimes cause parts of a crust to falter. Add crumbs to a medium-sized bowl and set aside.
Add nuts, brown sugar, cardamom, flour, and salt to the processor bowl and pulse until pecans are fine. Combine mixture with graham crackers in the medium-sized bowl. Mix well, then add the melted butter. Stir with a fork, spatula, or hands until the butter is even in distribution and coats the crumbs.
Add 3-4 Tablespoons of graham cracker mixture to each tart pan. Spread the crumbs evenly across the bottom of each tart pan. With a tart tamper, your hands, or the back and side of your smallest measuring cup, press the mixture into the bottom and up the sides of the tart pans. Refrigerate on a rimmed baking sheet for 10 minutes.
On the center oven rack, bake the tart crusts for about 10 minutes or until set and smell graham cracker fragrant. Let the crusts cool on the baking sheet on a wire rack.
Key Lime Filling
In a medium-sized bowl, beat the egg yolks and est with an electric mixer until light, airy, and fluffy, 4-5 minutes. Gradually add the sweetened condensed milk, while continuing to beat until the mixture is thick and fluffy, another 4 minutes. Reduce speed to low and slowly add the (key) lime juice until just blended. Pour the filling into the cooled tart shells.
Place the rimmed baking sheet, including the tarts on the center oven rack and bake until filling first appears set, between 10 - 12 minutes. The tarts may have a slight jiggle in the center.
Transfer the tarts to a wire rack and allow to cool completely. Tent loosely with foil and refrigerate until cold, at least two hours.
Fresh Whipped Cream
About 15 minutes before ready to serve, chill a medium-sized (preferably glass or metal) bowl and the beaters from your electric mixer in the freezer.
Using an electric mixer, beat the cream, confectioners' sugar, and cardamom until stiff peaks form. Avoid over beating.
Pipe or dollop these sweet tarts as you wish. Let me know what you think!
Notes
Technique adapted from Pie. My all time favorite "Pie Guy." High Altitude
the only change at 6,300 altitude, is using 5 tablespoons of butter in the crust vs. 4 at sea level.
Crust
brown sugar helps the crust hold together, but if your crumbs feel dry when mixing, wet your fingers with water and continue making the crust.
the crust can be made ahead, cooled, and covered. I've read crusts can be frozen too.
Pie Notes
four minutes is awhile to beat the eggs and zest, but so worth what waits on the other side! Some zest wraps around the beaters. I detangle and save the goodness.
I've made this pie with key limes and my gosh, four bags of zesting and juicing those tiny things later, I vowed to never again. The pie was amazing and sucker punched us in a different way, but limes are darn close. I never say never though, so may crave a change.
The amount of tart is up to you, for that reason, I include a range. One lime equals about 1.5 - 2 teaspoons of zest.
Whipped Cream Notes
for the best whipped cream, use a medium deep metal or glass bowl.
place the bowl and beaters in the freezer for a minimum of fifteen minutes.
whipped cream can be made early, covered, and refrigerated for up to a few hours.
this pie can be whipped and stored in the refrigerated for up to one hour, but after, it begins to "weep" or release liquid.