Lemon Curd

I had lemon curd the first time I visited my brother and sis-in-law in England.  I carried the recipe home with me - who  needs to buy souvenirs?  It's great on toast, as a pastry filling, in thumbprint cookies, etc.  Heck, just get a spoon and eat it straight from the jar...
Picture
Ingredients
2 lemons, fresh juice and zest
2/3 cup sugar
4 egg yolks, beaten
1/8 tsp salt
6 tbsp butter (unsalted) -  cut into cubes and soften to room temperature

Steps 
  1. Use a double boiler -   place a couple of inches of water in a pot and place another pot or heatproof bowl on top, so that the water warms it.  Bring water to a simmer. If you can't manage this, just turn the heat to low and use a regular pot.
  2. Place the beaten egg yolks, sugar, salt, lemon juice, and lemon zest into the top of the double boiler or in your pan.
  3. WHISK, WHISK, WHISK - for about 10 minutes until it thickens.  Try not to stop, as the egg yolks might curdle or your sauce might separate.  
  4. When it's nice and thick, remove from heat - then stir in the cubes of butter.
  5. Immediately  pour into a clean jar or bowl and cover with plastic wrap.  Gently press the plastic wrap onto the top of the curd.  This prevents a film from forming on your curd as it cools.
  6. When it's cool, remove the plastic wrap and cover jar or bowl with fresh wrap and refrigerate.
  7. It will keep fofr qbout 8 - 10 days in the refrigerator.