Preheat and prep: Heat your oven to 375°F (190°C). Lightly butter a small oven-safe skillet or a 9-inch baking dish.

Crush the Oreos: Break the Oreos into chunky pieces. You’re not making crumbs—aim for bite-size shards. Scatter half across the bottom of the pan.

Make the chocolate layer: In a microwave-safe bowl, combine semi-sweet chips, milk chocolate chips, heavy cream, butter, and a pinch of salt. Microwave in 20–30 second bursts, stirring each time, until smooth and glossy.

Assemble the base: Pour the melted chocolate over the crushed Oreos in the pan. Tap the pan gently to spread it evenly without losing the chunkiness underneath.

Add more Oreos: Sprinkle the remaining Oreo pieces over the chocolate, pressing a few lightly so they grip the surface.

Top with marshmallows: Cover the surface with mini marshmallows in a single layer. Keep them close together so they toast evenly and form a cohesive top.

Bake to gooey perfection: Bake for 7–10 minutes, until the marshmallows are puffed and golden. For extra toastiness, switch to broil for 30–60 seconds, watching closely so they don’t burn.

Cool slightly and serve: Let the dip rest for 5 minutes. Serve warm with graham crackers, fruit, or pretzels. Scoop straight from the pan.