Okay, here's the recipe (based on the recipe Danny found on the internet).
A special cast iron poffertjes pan, but you can also use a regular pan. It's kind of similar to a Danish æbleskiver or Japanese takoyaki pan, but more flat and has smaller holes.
1 cup flour
1 cup buckwheat flour
2 cups milk, at room temperature
1 tsp instant yeast
1 tsp salt
1/2 cup melted butter
1. If you're using fresh yeast, mix it with some milk in a cup or small bowl. Mix the flour, buckwheat flour, and salt in a large bowl. Add the yeast. Stir while you slowly add the milk first, then the egg, then the butter. Stir until you have a smooth mixture. Cover the bowl and let it rest for 45 minutes, at room temperature.
2. Heat the pan, and grease it with butter or oil. It should be sizzling hot. Fill the holes of the poffertjes pan for 75% with batter, or add spoonfuls of batter in circular movements to create mini pancakes.
3. Turn the poffertjes around as soon as the top has set (and the bottom is golden brown), using two forks, and fry until golden brown.
Serve hot. Poffertjes are typically served with butter and powdered sugar, but they can also be served with other sweet garnishes, such as syrup, whipped cream or strawberries.
A little tip from Ducky:
This is what I've found out after making dozens of poffertjes...it's wise to use a squeeze bottle when pouring the batter into the pan.