When the puff pastry is pliable, roll out to flatten and cut 12 squares or circles big enough for a muffin pan, about 3". Place pastry dough into muffin tin and place in freezer as you prepare filling.
Peel and dice shallots. Add a few tablespoons olive oil to a skillet over low heat and add the shallots, chopped rosemary, and a pinch of salt and gently caramelize.
In a bowl, add the cream cheese and slacken with the milk until you have a creamy paste. Add salt, pepper, and finely diced chives (or green onions) to create a savoury cheese spread.
Remove pastry from the freezer, and add about 1 tablespoon of the cream cheese spread to each tartlet. Use wet fingers to gently spread the cheese in the bottom of the tartlets.
Divide the caramelized shallots evenly across all tartlets.
Drizzle good quality olive oil and a few drops of balsamic vinegar to each tartlet, and then season with coarse salt, fresh ground pepper, and a pinch of finely chopped thyme.
Bake for about 20 minutes, or until the pastry is lightly brown.
