Using a large bowl, mix the yeast, salt and 3 cups / 360g of the flour.
In a pan, melt the butter and add the milk and honey and heat until just warm.
Add to dry ingredients and mix until combined and then stir in the cooked mashed butternut.
Mix in the remaining 3 ½ cups / 420g of flour and mix to combine.
Turn dough onto a floured surface and knead until smooth, about 8 to 10 minutes. Place in a lightly oiled bowl and let rise in a warm place for about 1 hour,until doubled in size.
After an hour, punch down the dough and divide into 24 equal pieces. Shape into rolls and place in a greased round baking pan. I use two baking pans, placing 12 rolls in each. Leave to rise again in a warm place.
Preheat oven to 375°F / 180°C. Brush tops with melted butter or beaten egg and sprinkle with seeds if using.
Bake until golden brown between 20-25 minutes.
Remove from the pans and place on a wire rack
Serve warm.