For Key Lime Curd:

1. In a mixer, beat together butter and sugar until light and fluffy.
2. Beat in one egg at a time, allowing to mix completely before beating in another egg.
3. Beat in key lime juice and zest until incorporated.
4. Over medium heat, in a heavy bottom pot or a double boiler, stir cream/egg/lime mixture. Stir mixture frequently until temperature reaches approximately 170 degrees and the mixture begins to thicken. Approximately 10 minutes.
5. Pour into bowl and let cool in fridge.

For Shortbread Crust:

1. Preheat oven to 350 degrees.
2. In food processor, combine all ingredients and pulse until mixture begins to resemble coarse meal.
3. Press into the bottom of an 8×8 inch baking sheet. Bake on middle rack to brown for 15 minutes, rotating half way through baking.
4. Remove from oven.

Final Assembly:

1. Pour key lime curd into the shortbread crust. Smooth curd so it reaches all corners of the crust.
2. Return to oven and bake for 30 minutes.
3. Remove from oven and allow to cool on a rack for two hours before cutting.
4. Slice, serve and devour.