Make the strawberry puree: preheat oven to 400, spread the berries onto a 9x9 square pan and bake (roast) for about 30 minutes until they have fully released their juices and some of the water has evaporated. While they are roasting, check on them and press them to help release the juices, about every 10 minutes. Puree the berries and set aside. This can be made a day or two ahead of time.
Make the starter: In a pot, whisk together the flour, water and milk. Continue whisking as it heats up and thickens. Once you have the consistency of a soft paste, remove from heat and allow to cool.
Make the dough: In the bowl of a stand mixer fitted with the dough hook attachment, combine the yeast and water. Sprinkle a bit of the sugar on top and whisk gently to combine. Give it a few minutes to proof.
Once the yeast mixture is foamy, add the rest of the ingredients as well as the starter. Turn the dough hook on and let it knead the dough until it comes together in a sticky mass, about 7-10 minutes.
Set the dough in a well-oiled bowl and cover with plastic wrap. Leave in the fridge overnight.
The next morning, remove the dough from the fridge. If it has not doubled in size, let it stand at room temperature to get there. This is to complete the first rise.
Make the filling, melt the white chocolate over a double boiler and stir it into the strawberry puree, add the strawberry powder or flour and mix.
Prepare a cookie sheet, a 9 x 13″ sheet cake pan or two 8×8” pans with parchment paper.
Roll the dough out into a 18 x 14 inch rectangle (about as big as a cookie sheet) and spread the filling over it, leave it for a bit so the filling firms up. Roll it up into a log and use a knife or dental floss to slice the buns into 1 inch pieces. Place onto the pan.
Set in a warm place for a second rise for about 45 – 60 minutes, until poofy.
Preheat the oven to 350. Bake the rolls for about 20-25 minutes, until sides are golden.
To make the icing: mix the cream cheese with the puree, vanilla and salt and powdered sugar. When rolls are cool, spoon it over the rolls.