This almond paste recipe yields approximately twice as much as you'll need for the gevulde koeken. You'll be able to freeze the leftovers. Zest the lemon.

Add the almonds, sugar, almond extract, and lemon zest into your food processor. Pulse until you see no more big pieces of almond; it should look like almond meal. Do not over process it, it can turn into almond butter.

Add the egg and keep pulsing until everything is fully combined.

Remove it from the food processor, and form it into a ball. Wrap it with cling film, and let it sit in the fridge for at least an hour. If you don't want to use the almond extract, you can omit it, and let the almond paste sit in the fridge for at least 2 days.

Zest the lemon

With a mixer, cream the butter, sugar, lemon rind, and salt together until fully combined.

Add the milk and egg, and mix them thoroughly.

Mix the baking powder into the flour.

Add the flour and baking powder, and mix until it's combined into a dough. You do not want to overwork it, which is why I often finish this by hand. You'll know it's done when the dough doesn't stick to your hands anymore.

Wrap the dough in cling film, and store it in the fridge for at least an hour.

Break the almond paste into small pieces, add the egg yolk, and water. Using your hands, or a mixer, mix it until everything is fully incorporated. It will be sticky!

Divide the filling into 12 even pieces, and roll them into balls. Cover with cling film, and set in the fridge for 30 minutes.

After the dough is done resting, divide it into 12 equal portions. Roll them in balls.

Let them rest in the fridge for 15 minutes.

Grease the muffin pan, and dust with flour.

Preheat your oven to 180ºC (350F) non-convection.

Roll each dough ball out until it's a big enough circle to completely cover one almond paste ball.

Wrap the dough around the almond paste, making sure there are no gaps.

Put the filled dough ball, seam down, in the muffin pan.

Repeat for all other dough, and almond paste balls.

Using a cup, flatten the filled dough balls. Fix any cracks by simply pinching them with your fingers.

Mix the egg yolk with the milk, and beat it until it's loose.

Put a blanched almond in the center of each rondo.

Brush the tops with the eggwash you've made.

Put the pan in the center of the oven.

Bake the rondo's for 25-30 minutes, or until they're golden brown. If your oven has hot spots, you may want to rotate the pan halfway through.

Let the pan cool on a rack for 5-10 minutes, then remove the rondo's from the pan, and let them cool completely on a rack.