Preheat the oven to 180ºC (350ºF).

In a large bowl, mix the sugar, cocoa powder, flour, and baking powder.

Add the melted butter and eggs, then gently mix with a rubber spatula until smooth. The batter will be thick.

Add the chocolate spread (if it’s cold, slightly warm it to soften) and mix well.

Fold in the chopped white chocolate and 10 crushed Oreo cookies. Stir gently to combine.

Pour the batter into a greased and parchment-lined 20x20 cm (8x8 inch) baking pan. If using a silicone pan, no lining is needed.

Bake for 30-35 minutes or until the edges start pulling away from the pan, and a toothpick inserted in the center comes out with moist crumbs but no raw batter. Keep a close eye on it and avoid baking for more than 36-37 minutes unless the center is significantly undercooked. Brownies should be slightly underbaked compared to cakes to achieve a soft, melt-in-the-mouth texture.

Let the brownies cool to nearly room temperature before slicing to prevent them from falling apart.

Store leftovers in the fridge for up to 5 days or freeze for up to 2 months. To serve, warm the brownies in the microwave for 10-15 seconds on low power or place them in a preheated (60°C/140°F) oven with the heat turned off for 5-10 minutes.