Line two large baking trays with baking paper.
Sieve the sugar into a bowl and reserve the lavender seeds.
Cream the butter and sieved sugar together until smooth.
Sift the flour and ground rice into the mixture.
Add the reserved lavender seeds and mix until the mixture resembles breadcrumbs.
Work the mixture with floured hands to form a smooth paste.
Knead the dough gently on a floured surface until smooth.
Chill the dough in the fridge for 15 minutes.
Roll the dough to a 5mm thickness and cut out heart shapes.
Place hearts on trays and sprinkle with extra lavender sugar.
Chill the trays in the fridge for another 30 minutes.
Preheat the oven to 180°C.
Bake for 15 to 20 minutes until pale golden-brown.
Cool on a rack and sprinkle with more lavender sugar.