In a saucepan over medium-high heat, melt the butter while whisking constantly. Continue cooking until the butter turns golden brown and gives off a nutty aroma, about 5–10 minutes. Immediately remove from heat and allow to cool for 5 minutes.

While it's cooling, whisk together the flour, salt, and baking soda in a bowl and set aside.

In a separate large bowl, whisk together the browned butter, brown sugar, and granulated sugar until combined. Add the eggs and vanilla extract, whisking until smooth.

Gradually stir the dry ingredients into the wet mixture until a soft dough forms. Fold in the chocolate chips.

Line one or two baking sheets with parchment paper.

Place a graham cracker square on the prepared sheet, spacing them about 3 inches apart. Top each with a square of baking chocolate and one marshmallow.

Scoop a generous portion of cookie dough, flatten it into a disc, and gently wrap it around the graham cracker stack, sealing the edges. Press extra chocolate pieces on top if desired.

Chill the prepared cookies in the refrigerator for 15 minutes to help them keep their shape while baking.

While chilling, preheat the oven to 350°F (175°C).

Bake for 12–15 minutes or until the edges are golden and the centers still look slightly soft. Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.

Sprinkle flaky sea salt on top if desired. Serve warm for that classic gooey s’mores experience.