1. Place sugar and yeast in a small bowl. Pour over warm water and leave to froth, about 5 minutes.
2. Sift 2/3s of the flour with the baking powder and salt into the bowl of your electric mixer. Add caster sugar, egg, buttermilk and softened butter. Add yeast mixture and mix together using mixer on a low speed. Add remaining flour and mix until dough comes together, but is still soft and slightly sticky. Add extra flour only if necessary - the dough should be quite soft.
3. Remove bowl from mixer and tip mixture onto your bench. Wash the bowl, oil with a little oil or butter, add the dough back to the bowl and roll it around in the oil to cover the surface to prevent a skin forming while it's proving. Cover bowl with plastic wrap and a tea towel and leave in a draught-free spot for 30 minutes or until doubled (ish) in size. (If you wish to premake this the night before, now's the time to get the mixture into the fridge to slowly prove overnight.
4. Tip dough out on to a lightly floured bench top, knead to bring together, then roll into a rectangle, 30cm x 20cm. Spread with 15g softened butter.
5. In a small bowl, mix together brown sugar,spices and dried fruit. Sprinkle over buttered dough. Starting at the widest side, roll up rectangle and pinch seam to seal. Cut roll into 12 slices.
6. Grease a 23cm square or round cake tin. Spoon in treacle, then add melted butter, brown sugar and pecans (if using). Fit sticky bun slices into the tin, leaving a small space between each. Cover tin with plastic wrap and tea towel and leave the dough to rise until doubled, about 1 hour.
7. Meanwhile, preheat the oven to 190°C.
8. Place sticky buns in the oven and bake for 30 minutes. Remove from the oven and immediately invert cake tin onto a serving plate. Serve Easter sticky buns warm.