Preheat the oven to 200°C.
Mix flour, salt, sugar, and yeast in a mixer, slowly adding up to 450ml of lukewarm water until a soft dough forms.
Cover the bowl with clingfilm and set aside.
Let the dough rise for 20 minutes until doubled, then roll it into a 60cm x 30cm rectangle on a floured surface.
Layer 1cm thick butter slices over two-thirds of the dough and fold the edges over to meet in the middle.
Fold the dough in half again.
Repeat the rolling and folding process three times, then wrap and chill in the fridge overnight.
Roll the chilled dough into a 5mm thick square.
Spread a mixture of cream cheese and vanilla over two-thirds of the dough, sprinkle with cinnamon, roll up, and cut into 4cm slices.
Place buns in a lined 23cm springform tin and leave to prove until doubled in size.
Brush with egg wash and bake for 20 minutes.
Simmer sugar, maple syrup, 25ml water, and bourbon in a pan until reduced and sticky, then brush over the warm cake.
Mix icing sugar with 1 tablespoon of water and drizzle over the buns.
Remove from the tin and serve.