The British know what they're doing when it come to toppings. Lime curd is delicious! It was so simple to make. I halved the ingredients from here and cooked it according to directions here. So, all in all, here is the recipe for
Cream together 1/4 cup butter with 1/4 cup sugar. Add three large eggs, mixing between each addition. Add the zest of one lime, and the juice of three limes (about a 1/2 cup of juice). Stir again. Transfer to saucepan, and stir over medium low heat for about 5-15 minutes. It will seem as though nothings is happening, and then all at once the eggs cook and your mixture thickens. Once this starts to happen, stir like crazy until you're sure the eggs are all cooked. Makes a little over a half pint. I've heard various numbers as to how long it will last in the fridge. One person said a week, another three weeks, another a month.
You could probably make lemon curd with this recipe too, just ignore the number of fruit - 1/2 cup fresh lemon juice.
I put in on toast, but it would be really good on scones too, or as a filling in a shallow tart. It's also pretty tasty by itself. There. You've been warned.