Melt butter in a light-colored saucepan over medium heat. Stir until foam subsides and milk solids turn amber and smell nutty, about 5–7 minutes. Transfer to a bowl, scrape in the browned bits, and cool for 15–20 minutes until just warm, not hot.

Spread pumpkin puree on paper towels and press gently to remove excess water.

In a large bowl, whisk brown butter, brown sugar, and granulated sugar until glossy. Whisk in egg yolk, vanilla, and blotted pumpkin until smooth.

In another bowl, whisk flour, baking soda, baking powder, salt, and pumpkin pie spice. Stir in graham cracker crumbs.

Fold dry ingredients into wet with a spatula until just combined. Stir in chopped chocolate.

Cover and refrigerate dough for 30–45 minutes.

Preheat oven to 350°F (175°C) and line two baking sheets with parchment.

Scoop 2-tablespoon mounds (about 40–45 g each), roll into balls, and arrange 2 inches apart on baking sheets. Flatten slightly with your palm.

Bake for 9–10 minutes until edges are set but centers look puffed and soft.

Press a marshmallow half, cut side down, onto each cookie. Return to oven for 2–3 minutes until marshmallows are glossy and starting to melt.

For caramelized tops, switch to broil on low for 20–40 seconds or use a kitchen torch. Watch closely to avoid burning.

Sprinkle with flaky salt and extra graham crumbs while warm. Cool on the tray for 10 minutes, then move to a rack.