Step 1

If you don't have a warm place to keep your batter, preheat the oven to 95°F - 104°F ( 35°C - 40°C. Turn the oven off when it gets to 104°F. The oven will act as a warm place for the batter to rest and help it rise.

Step 2

In a large bowl mix the 3/4 of the lukewarm milk with the yeast and sugar. (Make sure to use a bowl large enough for the batter to rise in without it overflowing)

Step 3

Add egg and flour and use a mixer with a dough hook to mix the batter. When the batter/dough starts to form, add the lemon zest and keep adding the rest of the lukewarm milk a little bit at a time while continuing to mix the batter. Keep mixing until you have a smooth batter.

Step 4

Add the melted butter and the salt and mix for a few more minutes till fully incorporated.

Step 5

Add raisins, currants, and apple to the batter and mix with a spatula till incorporated.

Step 6

Cover the bowl with a warm, damp cloth and put it aside in a warm place (or your preheated oven). Leave to rest for at least one hour.

Step 7

Once the batter has rested, take off the cloth and with a spatula, mix through the batter once.

Step 8

When the batter is almost ready to fry, turn on your deep fryer to 356°F / 180°C or you can fry the Oliebollen in a deep pan on the stove, just make sure you check the temperature regularly to ensure consistency while frying the Oliebollen.

Step 9

Dip with a metal ice-cream scoop into the hot oil, then scoop some of the batter with the ice-cream scoop and gently let the batter 'drop' in the hot oil. The batter will form immediately and float upwards. Depending on the size of your pan, you can fry several oliebollen at the same time. Just be careful not to overfill the pan. The oliebollen will expand a bit when they're in the oil and they need space to cook properly.

Step 10

Fry the oliebollen for about 5 minutes until golden brown and done, turning them halfway. Remove them from the oil and drain them in a dish covered with some paper towel or in a colander covered with paper towel.

Step 11

Serve the oliebollen lukewarm with some powdered sugar.