Sticky foods tend to be more difficult to cut through than others and toasted marshmallows may be one of the trickiest of all. Not only is the marshmallow gooey inside, but you need to preserve as much of the crisp exterior as possible and prevent the marshmallow from becoming completely smushed. Now, if you’re toasting marshmallows to make s’mores, you probably don’t need to cut them with a knife (being smushed between graham crackers with chocolate is definitely my preferred eating method!), but if you are baking a recipe that has a marshmallow topping, like my awesome S’mores Brownies, you need to be able to cut your finished baked goods into neat, even slices.
Fortunately, there is a foolproof method for cutting through a toasted marshmallow topping. It is best if your marshmallows are at room temperature, but this will work with very slightly warm marshmallow, as well. Warmer marshmallow is much stickier, so sometimes it is best to re-warm the dessert before serving if you want your marshmallow to be slightly melty.
Step 1 – Take out a sharp, serrated knife. Use vegetable oil to lightly grease it on both sides. Use a napkin or paper towel to ensure the oil is in a very thin layer.
Step 2 – Carefully cut through your marshmallow and brownie/cake/etc. in one cut, gently moving the knife back and forth.
Step 3 – Whip down the knife to remove all crumbs before starting the next slice.
The knife may need to be re-oiled if you are cutting a very large batch, but the oil will allow the blade to slide cleanly through the marsmallow and repel crumbs from the brownie/cake that could tear the marshmallow topping.