Bola de Berlim

Method

1. Whisk flour, 70g sugar, salt and yeast in a stand mixer bowl. Add warm milk, eggs and lemon zest.
2. Knead with the dough hook 6 minutes to a smooth dough. Add the soft butter in 4 pieces, kneading between each until incorporated.
3. Knead 5 minutes more until the dough is satin-smooth and pulls cleanly from the bowl.
4. Cover and prove 90 minutes until doubled.
5. Knock back gently. Divide into 10 pieces of about 75g each. Shape into tight smooth balls and place on a floured tray.
6. Cover loosely and prove 45 minutes until puffy.
7. Meanwhile make the doce de ovos: simmer 200g sugar, water, cinnamon stick and lemon peel 5 minutes to a thin syrup. Remove the cinnamon and peel.
8. Whisk the egg yolks lightly. Pour the warm syrup into the yolks in a slow stream, whisking constantly.
9. Return to the lowest possible heat and cook 4 to 6 minutes, stirring with a wooden spoon, until thick enough to coat the spoon. Do not let it boil. Cool, then transfer to a piping bag.
10. Heat the oil to 170C. Fry the bolas 2 to 3 at a time, 90 seconds a side, until deep gold; the oil must not be too hot or the centre stays raw.
11. Drain briefly on kitchen paper, then roll each warm bola in caster sugar.
12. Slit each bola along the side with a paring knife (do not cut through). Pipe the doce de ovos generously into the slit so a thick line of yellow cream shows along the cut.