Preheat oven:

Heat oven to 350°F (175°C) conventional or 320°F (160°C) convection.

Whisk wet ingredients:

In a big bowl, combine eggs, lemon zest, lemon juice, oil, granulated sugar, vanilla sugar, salt, and yogurt with a whisk until uniform.

Mix dry ingredients:

In another bowl, mix flour and baking powder with a whisk. Gently incorporate into the wet mixture until barely blended.

Fill muffin cups:

Insert paper liners into a 12-cup muffin pan. Evenly distribute batter among cups, filling each to roughly two-thirds full.

Bake and cool:

Bake 25 minutes until golden brown and a toothpick inserted in the center emerges clean. Let cool in pan for 5 minutes, then move to a wire rack to cool entirely.

Glaze and garnish:

In a small bowl, combine powdered sugar and lemon juice with a whisk until smooth and creamy. Drizzle over fully cooled muffins. Garnish as desired with Smarties, sprinkles, chopped pistachios, or lemon zest.