Yemas de Santa Teresa (Ávila Egg Yolk Sweets)

Instructions

1. Strain the yolks through a fine sieve into a heavy saucepan to remove any white.
2. Boil the sugar, water and lemon zest in a small pot, then simmer 8 to 10 minutes, until the syrup is slightly thickened. Remove the zest and cool completely.
3. Stir the cooled syrup into the yolks. Cook over medium-high heat, stirring constantly with a spatula, for about 7 minutes, until thick and the mixture reaches 160 F (71 C).
4. Remove from the heat and keep stirring 5 more minutes until it pulls away from the pan and looks like a thick paste.
5. Spread into a small lined loaf pan, cover and refrigerate for 24 hours.
6. Dust hands with granulated sugar, scoop 1 1/2-inch (4 cm) portions and roll into balls.
7. Roll each in powdered sugar, shake off the excess and place in small paper cups.