פירוש על עבודה זרה 75:9

The assumption here is that the person singed the head of the animal to remove the hair and not to cook it. Therefore, as long as the animal is kosher, the Jew can eat it even though the non-Jew performed a cooking activity with it.

The pumpkin, put into the oven by the Jew, was cooked by the non-Jew who threw a peg into the fire and then lit the stove. Therefore the pumpkin should be prohibited. But Ravina teaches us that his intention was not to cook the peg but to harden it, therefore the pumpkin is permitted. Again, we take the person’s intention into account.