Use a knife to slice the cold butter into very small cubes -about 1/4-inch sized cubes. Work these into the flour using a pastry blender until the mixture is coarse. Add 6 tablespoons of ice water to the mixture and use a spoon to toss it together. Add more ice water 1 tablespoon at a time, tossing it together with the flour-butter mixture with the spoon. Add water only until the dough is moist enough to hold together when you squeeze some in your hand.
Turn the contents of the bowl out onto a lightly floured surface, and knead gently 4-5 times: flatten it with the heel of your hand, fold up from the bottom, turn one-quarter turn and repeat. Do not over-knead the dough. Stop when the dough has just come together. There will still be pieces of butter visible in the dough. Divide the dough in half. Flatten each half slightly and wrap the disk in plastic wrap. Chill the dough disk in the fridge for 30 minutes or until firm.
For the curd:
In a stainless steel saucepan whisk together the granulated sugar, orange juice, orange zest, eggs and egg yolk until the mixture is smooth. Cook the mixture over medium-low heat, stirring frequently for 6-8 minutes until mixture is beginning to thicken. Remove the pan from the heat and whisk in the 2 tablespoons of butter into the curd until it has melted and mixed in. Set the curd aside.
Assemble the tartlets:
Preheat the oven to 400° F. Have ready a mini muffin pan.
Unwrap one chilled dough disk onto a lightly floured surface and roll out to about ¼-inch thickness. Use a cutter or drinking glass to cut out circles that are about 2 ½-inches in diameter. Press the circles into the cups of a mini cupcake pan, over the bottoms and up the sides of the wells.
Fill each cup almost to the top with orange curd (about 2 teaspoons.)
Bake the tartlets for 25 minutes until the crust edges and curd have started to brown. Use the tip of a knife to carefully pop the tartlets out of the pan. Cool them on a wire rack. Repeat with any remaining pastry dough and curd until they are all baked.
Make the cream:
Chill the bowl and whisk attachment of your stand mixer in the freezer for 10 minutes. Reassemble the bowl and whisk onto the mixture.
Pour the whipping cream into the bowl and beat the cream on high speed (just high enough that the cream doesn't go everywhere!) for 3 minutes. Add in the maple syrup, and beat the cream for about 3-5 more minutes, until stiff peaks have formed.
Top each tartlet with about a teaspoon of maple cream. Using a vegetable peeler, pull the peeler over the flat side of the chocolate bar to make curls. Top each tartlet with a curl or two.
Makes about 50 tartlets. Extra tartlets that are topped with cream and chocolate can be stored covered in the refrigerator up to 3 days.