Blue Cheese & Apple Stuffed Pork Tenderloin

You will need: 1 pork tenderloin (about 21 oz) 2 small shallots 2 cloves garlic 2 small pears 21⁄2 oz blue cheese a few twigs of rosemary 2 tablespoons olive oil 1 tablespoon butter 1 teaspoon salt a few turns of black pepper from the mill