Place the milk and butter in a small saucepan and heat gently over low heat until all the butter has melted.
Take the mixture off the heat. The mixture should be lukewarm. Add the sugar and yeast and stir well to avoid any lumps from forming. Leave to stand for 5 minutes.
In a separate bowl, add the flour, lemon zest, salt and spices. Stir, then pour in the milk mixture. Using a wooden spoon, stir to form a dough. Knead for around 10 minutes.
Place the dough in a lightly floured bowl and cover with cling film. Leave in a warm spot for 2 hours or until doubled in size.
Once doubled in size, take the dough out onto a lightly floured surface, knock the air out of the dough and gently knead in the frozen blueberries.
Shape the dough into six buns, then place them onto a baking tray lined with baking parchment and prove once again for around 40 minutes or until well risen.
Preheat the oven to 220 C | Gas Mark 7.
In a small mug or bowl, mix the plain flour with water to make a smooth, thick paste. Transfer the mixture into a freezer or a piping bag, snip off the corner and pipe crosses on top of each bun.
Bake in the middle of the oven for around 25 mins or until golden.
Brush with maple syrup or apricot jam while still warm.