Rhubarb Tartlets

Name: Rhubarb Tartlets
Ingredients: 1/2 cup (57g) confectioners' sugar; 8 tablespoons (113g) unsalted butter cold; 1/2 teaspoon salt; 1 teaspoon baking powder; 2 1/4 cups (255g) Pastry Flour Blend or 2 cups (241g); 2 large egg yolks; 1 large egg; 1 teaspoon vanilla extract; 5 cups (567g) rhubarb cut in 1" pieces; 1/2 cup (99g) sugar; 1 teaspoon vanilla paste or 2 teaspoons vanilla extract; 1 teaspoon Instant ClearJel optional for thickening; substitute 1 tablespoon flour if des; 1/2 cup (57g) King Arthur Unbleached All-Purpo; 1/4 cup (50g) granulated sugar; 1/4 teaspoon salt; 4 tablespoons (57g) unsalted butter cold cut into 1/2" cubes; 1/2 cup (57g) chopped pistachios