½ cup + ½ tablespoon (85 g)icing sugarpowdered sugar
a pinch of salt
¼ cup (40 g)hazelnuts
1.4 oz (40 g)dark chocolate
Place the butter and flour in a food processor and pulse until you have a sandy mixture.
Transfer to a large bowl, add the icing sugar, egg, lemon zest and salt.
Mix the ingredients with your hands then turn the mixture onto a work surface and knead until you have a smooth dough.
Wrap the dough with cling film and let it rest in the fridge for 30 minutes.
Roll out the dough about 0.19 inches (½ cm) thick and use a round cookie cutter to make the lids.
Roll the remaining dough into small logs, 2.5 inches (6 cm) long and curve them. These are the handles on top of the lids.
Place the lids on a baking sheet lined with parchment paper and attach the handle in the middle of the cookie. Put a piece of rolled parchment paper underneath the handle and keep it there until the cookies are out of the oven.
Chill the cookies for 30 minutes.
Preheat the oven to 347°F (175°C).
Bake the shortbread mug lid cookies for 15 minutes or until lightly golden, remove and place on a wire rack to cool.
Don't switch off the oven as you have to toast the hazelnuts.
Spread the hazelnuts in a single layer on a baking sheet and toast until the skins are mostly split and the nuts are light golden brown and fragrant (about 15 minutes).
Remove from the oven and rub the hazelnuts until the loose skins come off.
Let them cool completely and pulse in a food processor until chopped.
Melt the chocolate in the microwave.
With a small brush, spread the melted chocolate all around the side of the cookie then roll in the chop hazelnuts.
Put the shortbread mug lid cookies on a wire rack to dry.