Add the flour, sugar and salt in a mixer, food processor or large bowl.
Dice the butter up into small pieces and pulse or "cut" the butter into the dry mixture. You can use the pulse option, whisk or pastry cutter. The mixture will start to look coarse and chunky.
Because we are making mini tarts, we don't need to use the entire egg yolk. Break the yolk and use just ONE teaspoon of yolk.
Add 1 teaspoon of the yolk and ½ teaspoon of cream to the mixture and pulse or cut until the dough begins to come together in a ball or you are able to easily form it into a ball.
Wrap the dough and let it chill for 30 minutes - 1 hour. Doing this will allow you to roll it out easily without sticking.
Add some flour to your table and place your dough on top. Using a rolling pin, roll the dough into a round shape until it is ⅛" thick. After each roll, rotate the dough a few degrees to prevent it from sticking. It does not need to be a perfect circle.
Cut out rounds of dough that are about 2" in diameter. Then place the dough inside each muffin tin carefully pressing it down into the tin. If it rips, just patch it up with a little dough. (See photos.)
Preheat your oven to 375°F.
In a food processor or mixing bowl, add egg yolks and sugar and whisk until the color turns pale/light yellow. (about a minute or so)
Warm your milk in a small saucepan or in the microwave until hot but not boiling.
Add your warm milk, vanilla and nutmeg to the egg mixture and mix until fully combined.
Scoop or pour the custard into each muffin tin until they are just filled.
Bake on the middle rack for 14 minutes or until the custard SLIGHTLY jiggles.
Allow to cool a bit before removing. (Use a knife to release the sides until they pop out.) Grate or sprinkle more nutmeg on the top of each and chill until ready to serve.
Yield: 10-12I have not tried making these using a large muffin tin. If you do, I would double the ingredients and bake them longer.Remove your custard tartlets when they are warm enough to handle. If you want until they fully cool, they will be tougher to remove.Store tartlets in the fridge for up to 5 days.