Fortunately, key lime pie is really easy to make and only takes an hour or less. For this instructable, I will be using "Nellie and Joe's Famous Key West Lime Juice", because fresh key limes are hard to come by in Michigan. A local chef gave me this tip. It is almost impossible to tell the difference.
I will make the graham cracker crust, but you can buy one pre-made from the grocery store and that will save you at least half an hour.
Step 1: Gather Ingredients
16 graham crackers, crushed
1/4 lb. butter, or butter substitute
3 tbls sugar
or, buy a pre-made graham cracker pie crust
Key Lime Filling
1/2 cup "Nellie and Joe's" key lime juice, or the juice of 12 to 15 key limes
4 egg yolks
2 tsp lime zest
14 oz. can of sweetened condensed milk (NOT evaporated milk)
Step 2: Gather Tools
A way to crush the graham crackers
9 inch pie pan
Kitchen scale (optional)
Step 3: Crush the Graham Crackers
Step 4: Add Sugar and Butter
Stir it up.
Step 5: Place Mixture Into Pie Pan
Step 6: Bake the Crust
Step 7: Let's Make the Filling
Using the two halves of the egg shell, transfer the yolk back and forth over a cup. The white will drop off. Put the yolks in a separate bowl.
Stir the yolks up well. They should be a smooth, even, yellow consistency.
Step 8: Sweetened Condensed Milk
Warning: This is important. Make sure you get "Sweetened Condensed Milk", not evaporated milk. Many people make this mistake and the filling will not gel. They both come in cans and are sold next to each other at the grocery.
Step 9: Prepare the Lime
1a. (Optional Step)
Grate a couple of teaspoons of lime zest. Lime zest is the green outer skin. Do not grate the white skin from under the green. That is really bitter. Use a fine tooth grater. Add the gratings to the remaining juice. I have added the zest of a more common persian lime. I like the little green flecks in the pie. Ideally, you would add zest of the key lime. Or, you can skip the zest altogether.
2. Add the rest of the juice to the mixture and mix well.
Step 10: Fill the Cooled Pie Crust and Bake
Put the pie back in the oven for 12 minutes at 350 degrees.
After the 12 minutes, put the pie on a cooling rack. It should be set up and gelled now. Wait until it cools, then put it into the refrigerator for later.
Server with a dallop of whipped cream, if you like, but it is traditionally served without.