Step 1
Preheat oven to 180°C. Line 16 holes of two 1/3-cup (80ml) muffin pans with paper cases. Combine the poppy seeds and milk in a bowl. Set aside for 10 mins.
Step 2
Meanwhile, use an electric mixer to beat the butter, orange rind, lemon rind and sugar in a large bowl until pale and creamy. Add the eggs, 1 at a time, beating well after each addition.
Step 3
Add the combined flour and milk mixture, in batches, stirring until just combined. Divide the mixture evenly among the lined pans. Bake for 20-25 mins or until light golden and a skewer inserted in the centres comes out clean.
Step 4
While the cupcakes are cooking, place the orange juice, lemon juice and extra sugar in a small saucepan with 1 cup (250ml) water. Stir over medium-high heat for 4 mins or until the sugar dissolves. Increase heat to high and bring to the boil. Reduce heat to medium and simmer for 5 mins or until the syrup thickens slightly.
Step 5
Use a skewer to poke holes all over the surface of each warm cupcake. Spoon 1 tbs of the syrup evenly over each cupcake. Cool completely.
Step 6
To make the blackberry frosting, place the blackberries, sugar and 2 tbs water in a small saucepan over low heat. Cook, stirring, for 3-5 mins or until the berries start to release their juices. Cook for a further 3-4 mins or until the mixture starts to thicken slightly. Strain through a fine sieve into a bowl, pressing with the back of a spoon. Discard the solids.
Step 7
Use a clean electric mixer to beat the butter in a medium bowl until pale and creamy. Add the icing sugar, in batches, beating well after each addition. Add two-thirds of the puree and beat until well combined. Place the frosting in a piping bag fitted with a 1cm fluted nozzle.
Step 8
Pipe the blackberry frosting over the cupcakes. Transfer to a serving platter. Drizzle with the remaining puree. Sprinkle with thyme and extra blackberries to serve.