Finely chop your chocolate, and cut your butter into several smaller pieces.
In a saucepan, bring the cream and 1/2 teaspoon of the ground cinnamon just to a boil around the edges. Remove it from the heat and immediately dump in the chocolate and the butter. Let it sit undisturbed for a minute. Then gently, starting from the center of the pot, stir the melted chocolate into the cream in small circles. Stir in progressively larger circles (but still gently because you don’t want extra air to ruin the silky consistency), until it is completely mixed and is a uniform color.
Set aside and allow to cool for just a bit, around 10 minutes. Taste and add up to another 1/2 teaspoon of cinnamon to add a spicy flavor to the chocolate.
Pour the chocolate mixture into the pre-baked tart crust. Place it in the fridge and let it chill for at least 2 hours.
Serve chilled in thin slices with soft pillows of whipped cream mounded on top.
For the pecan tart crust:
Heat your oven to 400° F. Put the pecans in a food processor and pulse until you have a coarse, crumbly meal.
Grease a nine-inch tart pan with butter or line the bottom with parchment paper. Transfer the pecans to a bowl and blend in the honey (I use my fingers), then work in the chunks of butter with your hands. Press the mixture into a 9-inch round tart pan (it should fill the bottom and come just a little way up the sides) and put the pan on top of a rimmed baking sheet to catch any oil that may leak out as it bakes.
Bake in the oven for about 12 minutes, until browned and toasty. Remove from the oven and allow to cool completely.