• Preheat the oven to 375°. Prepare full-size muffin tins with 18 liners.
• In a large bowl, whisk together the white sugar with the lemon zest.
• Pour in the softened butter, yogurt, and eggs. Whisk until smooth.
• Add the flour, baking powder, baking soda and salt. Gently fold everything together until there are no more streaks of flour.
• Use a large spoon or an ice cream scooper to scoop the batter into the muffin liners until almost full to the top.
• Bake the muffins for 22-25 minutes. Remove from the oven.
• Next, brush lemon curd on top of each muffin top while they are warm (you will only use a portion of the lemon curd). Allow the muffins to cool completely on a wire cooling rack for 15 minutes, then remove from the pan.

Fill the muffins:

• Place remaining lemon curd into a pastry bag with a small round tip or in a squeeze bottle.
• Take a toothpick or a wooden skewer to create a hole in each muffin, poking the hole about  halfway down. Insert the tip and lightly squeeze the lemon curd into each muffin. Repeat the process into each muffin.