Brown half of the salted butter in a pan over medium heat until it turns golden brown and releases a warm, nutty aroma.

In a large bowl, combine the remaining softened butter with the brown and granulated sugars. Use an electric mixer to cream until fluffy and pale.

Add the egg and vanilla, mixing until smooth and fragrant.

In a separate bowl, whisk together the baking soda, salt, and flour. Gradually incorporate these dry ingredients into the wet mixture, stirring until a dough forms. Don’t overmix.

Gently fold in the rice krispie cereal using a spatula.

Scoop portions of dough (about a tablespoon each) onto a baking sheet lined with parchment paper. Flatten slightly and press mini marshmallows into the top.

Refrigerate the shaped dough for at least one hour.

Preheat your oven to 350°F (175°C).

Bake the cookies for 13-14 minutes, until the edges are golden and the marshmallows toast. The center should be just set.

Once out of the oven, sprinkle a touch of flaked salt over each cookie.