In a medium saucepan, bring the cream, butter and sugar to a simmer over medium heat. Whisk gently to make sure butter is melted and sugar is dissolved. If it is not, reduce heat and continue whisking until all is mixed and mixture is very hot, but not boiling - about 180 degrees on a candy thermometer.
Remove from heat; Submerge the chocolate under cream mixture and let sit for about 5 minutes. Stir with a rubber spatula to incorporate most of chocolate. Change to a whisk and whisk gently to smooth out remaining chocolate but not so enthusiastically that you form a lot of air bubbles.
Using a rubber spatula, go around all the bottom edges of the pan to make sure all of the chocolate is incorporated. This is extremely important when finishing the tart. If there are even teeny tiny lumps, it will not bode well as they will stick in the piping tip.
Pour 2 tablespoons of chocolate truffle filling over the caramel. Place in refrigerator to set up for several hours or overnight.
Lay out the remainder of the filling in a rimmed pan. Place plastic film directly over the filling and leave at room temperature for several hours or overnight. It needs to be soft enough to pipe but firm enough to hold its shape. If it becomes too firm, place it in a 200°F oven very briefly to soften it
Fit a pastry bag with a #48 basketweave tip. Starting at the top of the tart, pipe 4 straight lines from left to right about ½ inch apart. Turn the tart 90° (¼ turn) and, again, starting at the top pipe another set of straight lines left to right ½ inch apart. Lastly, turn another 90° (¼ turn) and pipe the last set of lines. You will now have the basketweave design.
Last, finish the edges of the tart with a ribbon design or another of your choice. Refrigerate to set.
To release the tarts, let them sit at room temperature for a bit and slide the side down. Place a metal spatula between the bottom of the crust and the removable bottom. If the tart is cold enough, it will pop right off with a twist of the spatula. Otherwise, go under the tart with the spatula and lift it off.
To Serve: Place in the cooler to firm up briefly if making ahead. Store in the refrigerator; but serve at cool room temperature. This can be made several days ahead as long as it is protected from odors in the refrigerator or it freezes well if covered.