Add the Oreo cookies to a food processor and pulse until they become very fine crumbs.

Pour in the melted butter and pulse again until the crumbs are evenly moistened. If you don't have a food processor, finely crush the cookies and combine them thoroughly with the melted butter.

Transfer the cookie mixture to a 9-inch tart pan.

Press the crumbs firmly and evenly across the bottom and up the sides of the pan. The flat bottom of a measuring cup works particularly well for compacting the crust.

Refrigerate the Oreo crust while preparing the chocolate filling.

Add the semi-sweet chocolate chips, heavy cream, butter, and granulated sugar to a medium saucepan.

Place over medium-low heat.

Stir continuously until the chocolate and butter have completely melted and the mixture is glossy and smooth. Don't allow the ganache to boil.

Taste carefully once slightly cooled and adjust the sweetness if desired.

Immediately remove the smooth chocolate filling from the heat.

Take the chilled crust from the refrigerator and slowly pour the ganache into the center.

Gently spread the filling into an even layer if necessary.

Allow the No-Bake Chocolate Tart to cool at room temperature for approximately 10 minutes.

Transfer the tart to the refrigerator and chill for at least 4 hours, or preferably overnight, until the chocolate filling is completely set.

Shortly before serving, arrange fresh berries over the chilled tart.

Lightly dust the berries with powdered sugar.

Slice with a sharp knife and serve chilled.