Beat the eggs and sugar in a large bowl until the sugar is completely dissolved.
Sift the flour, salt and baking powder together in a separate bowl and then add to the egg and sugar mixture. Whisk until just incorporated.
Add the olive oil, milk, and lemon zest and whisk until well combined.
To achieve the spongy texture of a Spanish magdalena, you'll need to let the mix rest in the fridge. Cover the bowl with plastic wrap and leave in the fridge for 1 hour.
Preheat the oven to 480°F (250°C).
Line muffin trays with muffin wrappers.
Fill the muffin wrappers 3/4 of the way, and, if you'd like, sprinkle a pinch of sugar on top of each muffin. This will form the sugary crust that is typical of the Spanish magdalena.
As soon as you put the muffins in the oven, lower the heat to 400°F (200°C). Bake for 15 minutes on the middle rack, don't open the oven until you think they're ready.
Test with a toothpick in the middle of a muffin to make sure they're cooked through
Let your magdalenas rest for at least five minutes before enjoying!