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.
White Chocolate Ganache
Place white 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 white chocolate. Let sit for about 2 minutes and then stir until the white chocolate is completely melted and smooth.
Pour the white chocolate into the shell and place in the fridge for 30 minutes to set.
Dark Chocolate Ganache
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 tart until the white chocolate is completely covered. Place back in fridge for 30 minutes or until set. Sprinkle some salt over tart and serve cold.
Notes
Skip baking the crust if you want a super crumbly tart.
The lighter the chocolate the less cream you need which is why the white chocolate uses less..
Use quality chocolate as it contributes to the flavor of the tart.
If the ganache is too think, 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.