Here’s the rest of the recipe:
Pre-heat oven to 325 Fahrenheit. Grease 2 muffin tins well with butter. Using a fork, mix well the sugar and eggs in a large bowl. Add the flour, a bit at a time, until completely blended. Set aside. In a saucepan over medium heat, slowly boil the milk, butter and lemon
skins. Be sure to stir continuously. Once boiling, remove the lemon
skins and remove milk from heat. Add the milk to the sugar mix, but do NOT pour it in all at once. Make sure to pour only a small amount at a time, and mix well with a mixing spoon, repeating this process until all milk is added. This will ensure to slowly warm the sugar mix,
without cooking the eggs. Add to the muffin pans evenly, stirring mix
about half way to prevent separation.
Place in oven. Bake until edges are golden brown and tops are slightly golden (or to preferred color). You may need to lower the heat if it appears edges are cooking too quickly. Tarts may rise out of pans, and/or bubble up in the middle while baking, but they will go back down. Estimated time is 20 min, but could vary greatly (I once had themin the oven for 40 min at a lower temperature, but normally 20-30 is typical), depending on your oven. Remove from pans
immediately (using a butter knife and fork to separate edges from the pans and lift them out are found to work best) and place on cooling racks or plates. Sprinkle cinnamon across the tops and let cool. If eaten immediately, centers will be soft and may appear not completely cooked. Texture will change as it cools. May be eaten at room temperature or chilled as well. Enjoy!
Note: Don’t be surprised if some of the batch turns out well and some don’t. These tarts tend to be temperamental.