• Freeze the marshmallows. Spread them out on a parchment lined baking sheet and place it in the freezer for 20 minutes while you make the cookie dough.
• First brown the butter. Follow the instructions in this post here to learn how to brown butter. It’s easy! Melt it in a medium saucepan and continue to cook allowing it to gently boil over medium heat. It will start foaming and turn golden brown with a nutty aroma. Make sure you are stirring and watching closely so it doesn't burn. Brown specks and a dense golden foam will form at the surface when it is nearly ready. This whole process takes around 8-10 minutes. Immediately pour it into a large mixing bowl and let it cool for 20-30 minutes until it reaches room temperature and is fluid but no longer hot.
• Add brown sugar, granulated sugar, honey and vanilla to the cooled brown butter and mix with a spatula until it is combined and starts to look a little fluffy. I prefer not to use a whisk at this point because if you incorporate too much air or cool the brown butter too much, the mixture will stiffen up.
• Add the egg and mix well until evenly incorporated and the mixture looks smooth and sort of syrupy.
• Combine flour, baking soda and salt in a medium bowl and whisk to blend evenly. Add this to the brown butter mixture and fold it in. When most of the flour is incorporated, it will look a bit dry and now you can add the teaspoon of milk. Continue folding the dough until the ingredients are evenly combined. Add crispy rice cereal and ¾ cup (38g) of frozen marshmallows, then fold them through so they are evenly distributed.
• Use a 1.35-oz cookie scoop to portion dough and then roll into balls. Place the dough balls on a parchment-lined baking sheet and freeze, uncovered, for 30-60 minutes. This hardens the marshmallows so they hold their shape better during baking.
• Preheat oven to 325°F (or 350°F if you prefer thicker cookies as described in the EXPERT BAKING TIPS above). Line two large cookie sheets with parchment paper.
• When ready to bake, place dough balls onto prepared baking sheets spacing them 3 inches apart. Press 2 more frozen marshmallows on top of each ball, but tuck them in under the dough or push some cookie dough up around them so they don’t burn and ooze out of the cookie. Flatten dough balls slightly so they spread evenly if you prefer thinner cookies. Bake for 9-11 minutes until lightly golden all over and still soft in the middle. If you bake at 350°F, then you'll need 8-10 minutes. Let cookies cool for 1 minute on the baking sheet then transfer to a wire rack to finish cooling.

NOTE: I don't always have to freeze my dough to get the desired results, but it can help control how much the cookies spread. I find that it really depends on the brand of marshmallows that you use since some varieties can melt into sugar puddles very quickly.