Preheat oven to 350. Spray 9" spring form pan with butter spray.
Pour crumbs into pan along with melted butter. Combine mixture with a fork until well blended. Press mixture with your fingers along the side of the pan up to the edge about an inch and along the bottom to make a crust.
Bake for 6 minutes. Set aside to cool.
While it's baking, make filling.
Mix all ingredients with a spoon or your mixer on low speed. You need to do this while chocolate is HOT.
Be sure to keep mixing until the mixture is completely brown and no white streaks of mascarpone cheese.
Now pour the filling in the cooled crust and put the tart in your refrigerator. It needs to be refrigerated at least an hout to firm up.
After an hour, you will need to cover it with plastic wrap so it doesn't get a film on top.
You can sprinkle powdered sugar on top before serving.
IMPORTANT HINT: Take the tart out of the refrigerator about an hour ahead of serving. It tastes so much richer when it's just slightly cool and not cold. YUMMY!