Remove the pears from the juice but be sure to keep the juice.
Lay the pears, cut side up, in the pan. I can my pears with the skins on. If yours don't have skins, just lay them in the pan.
Spoon five tablespoons of the pear juice over the top of the pears.
Wash the fresh rosemary under cold water quickly. Shake to dry.
Remove the rosemary leaves from the stems and place the rosemary on top of the pears. I put my rosemary leaves on whole but you can chop the leaves up if you prefer. We did this the second time we made this recipe and actually liked it better because I don't like eating crunchy rosemary.
Cut the butter into small pats and place one pat on top of each pear.
Place the pan in the oven. I do not preheat my oven. You can if you want to.
Bake the pears at 375 degrees F for 30 to 40 minutes basting every 10 minutes. When they are done the liquid is a thick syrup, the pears are soft and may have a slight brown color to them.