Preheat your oven to 180°C (350°F). Line a standard muffin tin with paper liners or grease the molds with cooking spray or butter.
In a large mixing bowl, beat the eggs with an electric mixer or whisk until they become light and frothy.
Gradually add the granulated sugar while continuing to beat the eggs. Beat until the mixture is pale and creamy.
Mix in the vegetable oil (or melted butter) and vanilla extract, continuing to beat until well combined.
In a separate bowl, whisk together the flour, baking powder, and a pinch of salt.
Gradually add the dry ingredients to the wet ingredients, stirring gently until just combined. Avoid over-mixing, as this can result in dense magdalenas.
Add the lemon zest to the batter and fold it in gently to distribute the flavor.
Cover the bowl with plastic wrap and refrigerate the batter for at least 30 minutes. Chilling the batter helps the magdalenas rise properly during baking.
After chilling, fill each muffin mold about two-thirds full with the batter.
Bake the magdalenas in the preheated oven for about 15-20 minutes or until they turn golden brown on top and a toothpick inserted into the center comes out clean.
Remove the magdalenas from the oven and let them cool in the muffin tin for a few minutes. Then, transfer them to a wire rack to cool completely.
If desired, sprinkle powdered sugar on top of the magdalenas before serving.