Birthday Cake cinnamon buns are a glorious treat to make to celebrate. If someone doesn't like cake, this is for them! It's loaded with sprinkles and cinnamon filling, they're really fluffy and so fun and colourful!
Heat the milk until it’s warm. Add the sugar and sprinkle over the yeast. Whisk to combine and let it sit for a minute or two. Pour in the vanilla and butter and whisk through. Add in the flour and mix until a soft dough forms.
Transfer the dough to a lightly floured surface and knead until smooth. Let it sit for 10 minutes then roll it out slightly. Scatter over the sprinkles and fold the dough to combine them. Transfer to a greased bowl and cover to let rise until doubled in size.
With a hand mixer, whip together the filling ingredients until smooth. Set aside.
Once the dough has doubled in size, punch it down and transfer to a lightly floured surface. Roll the dough out into a large rectangle about ½ cm thick. Spread the cinnamon butter filling all over the dough, leaving a 1cm border bare.
Roll the dough up into a tight log from the long side. Measure the dough into 9 even pieces, then using floss slide it under each piece, cross over the floss and crossover to cut
Arrange the rolls about 2cm apart on a lined baking sheet. Cover and let them rise again until doubled in size.
Preheat the oven to 180ºC with a rack in the middle. Mix all the frosting ingredients together in a bowl until smooth.
Once the rolls have doubled in size and look airy, pop them in the oven and bake for 25 minutes, until golden brown. Set aside to cool slightly
While the rolls are still warm, spread the frosting over top and add some sprinkles.
