Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats.

In a medium bowl, whisk together 2 3/4 cups all-purpose flour, 1 teaspoon baking soda, and 3/4 teaspoon fine sea salt. Set aside.

In a large mixing bowl, beat 1 cup (2 sticks) unsalted butter, softened with 3/4 cup granulated sugar and 1 cup packed light brown sugar until light and creamy, about 2–3 minutes. Use a hand mixer or stand mixer on medium speed.

Add 2 large eggs, one at a time, beating well after each addition. Mix in 2 teaspoons vanilla extract until smooth.

On low speed, add the dry ingredients to the wet ingredients and mix just until combined. Don’t overmix.

Fold in 1 1/2 cups chocolate chips and 1 cup roughly crushed graham crackers. You want the graham pieces to be small chunks, not crumbs, for better texture.

Scoop dough into balls, about 2 tablespoons each (a medium cookie scoop works great). Place them 2 inches apart on the prepared sheets.

Press 3–4 mini marshmallows gently into the top of each dough ball. Don’t bury them—leaving them on top helps prevent melting messes.

Bake for 9–11 minutes, or until the edges are set and lightly golden but the centers still look slightly soft. If the marshmallows get too toasty, tent loosely with foil for the last minute.

Right out of the oven, use a spatula to nudge any runaway marshmallow back onto the cookie. If you like, add a few extra chocolate chips and a pinch of flaky sea salt on top for a bakery look and balanced flavor.

Let cookies cool on the baking sheet for 5–7 minutes, then transfer to a wire rack to cool completely—or enjoy warm for maximum gooeyness.