Preheat the oven to 375°Fahrenheit/190°Celsius and place 9 muffin liners in a muffin or cupcake pan.
In a large bowl, mix the white sugar with the lemon zest to help release the lemon oils. Do this using a whisk or your hands until the sugar is a pale yellow.
½ cup white sugar, 1 tablespoon lemon zest
Pour in the melted butter, yogurt, and egg. Whisk until smooth.
1 stick unsalted butter, ¾ cup yogurt, 1 large egg
Pour in the flour, baking powder, baking soda and salt. Use a rubber spatula to fold everything together until there are no more streaks of flour.
1 ¾ cup all purpose flour, 2 teaspoon baking powder, ¼ teaspoon baking soda, 1 teaspoon kosher salt
Use a spoon or an ice cream scooper to scoop the muffin batter into the liners until each liner is almost full to the top.
Bake in the preheated oven for 22-25 minutes.
Take the muffins out of the oven and use a pastry brush to brush lemon curd on top of each warm muffin top. Let the muffins then cool in the pan for 15 minutes, then take out of the pan and let them cool completely on a wire cooling rack.
½ cup lemon curd
Once the muffins are completely cool you can fill them with lemon curd. Put the remaining lemon curd into a pastry bag with a small round tip or in a squeezy bottle.
Using the tip of the squeeze bottle, a toothpick or a skewer to create a hole at the top of each muffin. Poke this hole until about halfway down each muffin. Insert the piping bag tip or the squeeze bottle and gently squeeze the lemon curd out into the middle of the muffin. Repeat with the remaining muffins.
Notes
My recipes have been developed and tested in cups and metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. Just click on 'METRIC' above the ingredients. Butter: I use European style butter in my recipes. This will make your finished bake much creamier and richer.Lemon Curd: you can use store bought lemon curd or you can make my homemade lemon curd recipe. Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt. Please note I am using Diamond Crystal kosher salt and not coarse kosher salt (like Morton salt) which is far too salty for this recipe. Number of Muffins: this recipe makes 9 tall muffins instead of 12 - I would rather have 9 super tall muffins than 12 small muffins! Need to make more than 9? Double the recipe to make 18 muffins! Storage: keep the muffins in an airtight container in the fridge for up to 4 days.