Using a food processor, pulse the Oreos until finely ground. Transfer to a bowl with the melted butter and mix to combine.
Press into the bottom and sides of a 9 inch tart pan and place in the fridge for 30 minutes.
Preheat the oven to 350°F. Bake the shell for 8-10 minutes and then let cool completely on a wire rack.
Place dark chocolate in a medium bowl. Heat the cream and butter in a small saucepan over medium heat until it begins to simmer. Pour cream mixture over the dark chocolate. Let sit for about 2 minutes and then stir until the dark chocolate is completely melted and smooth.
Pour over the crust and smooth it out. Place in fridge for 30 minutes or until set.
After chilling, arrange raspberries on top by placing them with the pointed end facing upwards and positioned closely together.
Notes
Skip baking the crust if you want a super crumbly tart.
Use quality chocolate as it contributes to the flavor of the tart.
If the ganache is too thick, stir in a some more warm cream and if too thin, add some more chocolate in tablespoon increments.
You can store the tart in an airtight container for a week in the fridge or 3 months in the freezer.