Prep the pan and oven. Preheat your oven to 350°F (175°C). Lightly grease a mini muffin tin with nonstick spray or butter. This helps the bites release cleanly.

Crush the Oreos. Add the cookies to a food processor and pulse until you get fine crumbs. No processor? Place them in a zip-top bag and crush with a rolling pin. You want a sand-like texture.

Make the batter. In a bowl, stir the Oreo crumbs with the melted butter, egg, milk, vanilla, and a pinch of salt. Mix until it forms a thick, scoopable batter. It should be slightly sticky but workable.

Portion the base. Spoon a heaping teaspoon of batter into each muffin cup. Use the back of the spoon to press it down and slightly up the sides, creating a shallow well.

Add the Nutella. Place about 1 teaspoon of Nutella into the center of each well. Try to keep it in the middle so it stays molten and doesn’t leak to the edges.

Cover the tops. Add another small spoonful of batter over the Nutella to seal it in. Smooth the tops gently. Don’t overfill—keep them just below the rim.

Bake. Bake for 8–10 minutes. You want set edges and a slightly soft center. If you bake too long, the lava effect will be reduced.

Cool briefly. Let the bites rest in the pan for 5 minutes. This helps them firm up just enough to remove without breaking.

Release and finish. Run a thin knife around the edges, then lift out carefully. Dust with powdered sugar or sprinkle with flaky sea salt or crushed hazelnuts if you like.

Serve warm. These are best enjoyed warm so the centers are gooey. If they cool, you can rewarm them for a few seconds in the microwave.