Cups: Preheat oven to 400°F. Press a slice of pancetta into each cup of a mini muffin tin. Press a second tin on top of the pancetta. Bake for 12 minutes.
Make the hash: In a large skillet over medium heat, cook the bacon until crisp. Remove the bacon and add the potato, scallion, garlic, and rosemary to the skillet, then sauté until soft, about 10 minutes. Add crumbled bacon and keep warm.
Remove the pancetta cups from the tin and fill with a spoonful of hash. Top with a crumble of blue cheese and chives. Serve while warm.