In a large bowl, whisk together the flour, sugar, salt, and baking powder.
In another bowl, beat the eggs and then add the milk, melted butter, and vanilla extract. Mix well.
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix; a few lumps are okay. If using, add a pinch of nutmeg or cinnamon to the batter.
Heat a poffertjes pan or a regular non-stick griddle over medium heat. Lightly grease the pan with melted butter or oil.
Spoon a small amount of batter into each well of the poffertjes pan, or pour small dollops of batter onto the griddle. Cook for about 1-2 minutes on each side, or until golden brown and puffed up. You may need to flip them with a fork or small spatula.
Remove the poffertjes from the pan and place them on a serving plate. Dust with powdered sugar.
Enjoy your meal!