In a medium bowl, whisk together eggs, sugar, tangerine zest and juice, and salt until combined. Very gradually add melted butter, 1 tablespoon at a time, to egg mixture, whisking constantly after each addition so egg mixture doesn’t curdle. Return mixture to saucepan.
Cook over medium-low heat, stirring constantly until thickened, approximately 15 minutes. If mixture begins to scorch, lower heat. (Thickened mixture should coat back of the spoon and hold a line when finger is drawn through mixture, reaching a temperature of 175° with an instant-read thermometer.)
Using a fine-mesh sieve, strain mixture into a bowl. Cover, and refrigerate until needed, up to a day.
Preheat oven to 450°. Spray 12 (2½-inch) fluted tartlet pans with cooking spray.
On a lightly floured surface, unroll both sheets of piecrust dough. Using a rolling pin, roll out dough to a 1/16-inch thickness. Using a 3-inch round cutter, cut 12 circles from dough, discarding scraps. Transfer each round to a prepared tartlet pan, pressing into bottom and up sides. Using the wide end of a chop-stick, gently press dough into indentations in sides of pans. Trim excess dough. Using a fork, prick bottom of dough in each tartlet pan with a fork. Place prepared tartlet pans on a rimmed baking sheet. Freeze for 15 minutes.
Bake until pie dough is light golden brown, 5 to 7 minutes. Let cool completely.
Divide tangerine filling among prepared tartlet shells. Place tartlets in a single layer in a covered container, and refrigerate until cold, 2 to 4 hours.
Place Sweetened Whipped Cream in a piping bag fitted with an open-star tip (Wilton #21). Pipe a petite rosette of Sweetened Whipped Cream in center of each tartlet.
Garnish with tangerine zest strips, if desired.
Recipe by TeaTime Magazine at https://teatimemagazine.com/tangerine-tartlets/