Line a baking pan with a Silpat silicone baking mat. Set aside a mini muffin tray.
Shred 2 oz of the cheese in a food processor fitted with a shredding blade. Pour cheese into a bowl and set aside. Change blade to chopping blade and grate remaining 2 oz of cheese. Add 1/2 tsp chopped rosemary and process until cheese and rosemary are finely grated and incorporated. Mix all cheese together and combine well.
Working in batches, 4-6 at a time, place 1 1/2 Tbs cheese mixture in mounds on the Silpat, and lightly press down with the back of a spoon until even thickness, about 2" rounds. Bake for 6-8 minutes or until cheese is melted and just starting to turn golden at the edges.
Remove from oven, and let cheese cool for 30 seconds or so, just to set. Working quickly, lay one round of cheese over the muffin tin opening, and gently press in to make a basket/tartlet shape. Repeat with remaining rounds. Let cool, and gently remove cheese tartlets from the muffin tin. Repeat with remaining cheese.
Set aside cheese tartlets to cool.
In a saute pan, melt butter, and add chopped pears, honey, nutmeg and rosemary sprig. Saute until pears are soft and slightly caramelized. Remove from heat, and let cool a bit.
Remove rosemary sprig from pears. Spoon 1 tsp of pear mixture into each tartlet.
Sprinkle with a few chopped pistachios.
Serve warm or at room temperature.
When making the cheese tartlets, work in small batches, as the melted cheese will set up quickly. Tartlet shells can be made several hours in advance and kept in an airtight container. Fill with pears just before serving.