Making Stroopwafels is slightly time-consuming and requires a special waffle iron with a fine pattern or a wafer toaster that can create thin discs. However, the result is well worth the effort!
The caramel filling (Stroop) must be cooked until thick and sticky. The wafers must be cut immediately after baking while still hot and then filled, as they become brittle upon cooling.
In a small bowl, mix the yeast with warm milk and a pinch of sugar. Let it activate for 10 minutes.
In a large bowl, mix the flour, sugar, and salt. Add the softened butter, egg, and activated yeast. Knead into a soft but non-sticky dough.
Cover and let it prove in a warm place for about 1 hour until it doubles in size.
In a saucepan, mix the caramel syrup, butter, brown sugar, and cinnamon. Heat over medium heat, stirring until the butter and sugar dissolve.
Increase the temperature and let the filling boil for 5 minutes. Allow it to cool slightly (it will thicken) – it needs to be warm but not boiling so it can be spread.
Divide the dough into 12 equal balls. Preheat a waffle iron with a fine pattern (or a thin wafer toaster).
Bake each ball for 1-2 minutes until golden brown and thin. Immediately after removing the wafer from the iron, horizontally cut it into two thin halves with a sharp knife (you must work fast while the wafer is still soft).
Spread the bottom half of the wafer with the warm caramel filling and cover with the top half. Seal the wafers and let them cool on a rack. The filling will set, and the wafers will become crisp.