Combine flour, yeast, sugar, mixed spice, cinnamon and salt in the bowl of a stand mixer.
Attach a dough hook in the mixer and add butter, milk, egg, sultanas and orange zest to the flour. Mix until a smooth elastic dough forms about 5 minutes. If dough is sticky and doesn’t come away from the side of the bowl, add another ¼ cup flour.
First rise: Leave dough in the bowl and cover with plastic wrap. Place in a warm spot to rise until doubled in size. Note: this can take anywhere between 1 hour to 1 ½ hours depending on how warm it is.
Grease a large Bundt pan with melted butter.
Remove plastic wrap from the bowl and punch down the dough to deflate.
Dust work surface with flour and knead for one minute, then cut dough into pieces and roll into golf size balls.
Make the syrup by melting the butter and whisking in the sugar, vanilla and cinnamon.
Roll each ball of dough into the syrup and line them up randomly in the bundt tin.
Second rise: let dough in bundt tin sit for another 30 minutes to allow the dough to rise again.
In the meantime, pre-heat oven to 180°C. Place the bundt pan in the oven and bake for 30 minutes or until top is a golden brown.
Remove from oven and allow to cool for just a few minutes before turning the ring onto a plate to serve.
In a medium bowl, whisk together the icing ingredients until smooth and drizzle over the pull apart. If the icing is too thick, add a touch more milk and if it's too runny, whisk in a little more icing sugar until you get a pourable consistency.