I've made these with regular lemons, Meyer lemons, a leftover tangerine, blood oranges, limes and key limes. My favorite combo is 1 lemon and 1 key lime per original recipe batch (we usually double it). If you double the recipe, use 3 lemons if they're all you use. Strictly speaking, these are less muffins and more little syrup soaked cakes made according to the muffin method. If you want a finer, more tender crumb, use sour cream instead of yogurt.
Ingredients:
1 cup (4.5oz) all-purpose flour
7 tbsp granulated sugar
0.5 tsp baking SODA
6 tbsp butter (if unsalted, add a big pinch of salt)
0.5 cups plain whole milk yogurt
2 large eggs
Zest of your citrus
1 tsp vanilla extract, optional
Juice of the citrus
Extra sugar for the soaking syrup
Preheat oven to 325F and spray either a "Texas-sized" 6 cup muffin pan or a normal sized 12 cup.
Put the flour, sugar, zest and baking soda into a decent sized mixing bowl, and stir with a fork or whisk until evenly combined. Yes, this is superior to sifting together; just trust me. In a 2-cup Pyrex measuring thing, microwave the butter until it is just barely melted -- stop and just stir it to meltiness when 80% of the butter is liquid and only a little soft remains. To the measuring cup, add the eggs and yogurt and beat until emulsified. Pour the liquid ingredients into the bowl of dry ingredients and stir until combined. Some lumps are okay. Then pour into your baking tin and bake for 20-30 minutes or until the edges are a little browned and a toothpick comes out clean.
While the muffins bake, take roughly a quarter cup of the juice and add about 125% of its quantity of white sugar, then microwave until it all dissolves. You want a fairly tart but still quite sweet simple syrup, using the citrus juice in lieu of water. (Leftover syrup makes awesome lemonade.) As soon as the muffins come out of the oven, use a skewer to poke them repeatedly then pour a thin covering of syrup over top of each one. If any muffins are already dry by the time you've doused them all, pour a little more syrup over top. Let them cool, then eat!