Lemon Curd

From my friend Marcy's blog

Zest and juice of 2 lemons
1 cup of sugar
1/2 cup butter
3 whole eggs
1 egg yolk

Put zest, juice, butter & sugar in a glass bowl. Microwave for 1 minute and stir. Microwave for another minute and whisk well until butter is melted and sugar is dissolved. In a seperate bowl, whisk the eggs and additional yolk well. Add a little of the lemon mixture to warm up the eggs and then whisk the eggs into the lemon mixture. Microwave on high for 30 seconds, whisk, and repeat this process until mixture is thick and creamy. Usually takes about 5 times of microwaving and whisking. Can be refrigerated for 2-3 weeks. Good on toast, scones, etc.