1-First Step: Prepare the Mise en Place Measure all ingredients accurately. Soften butter to room temperature for easy creaming. Have flour sifted and jam ready. Line baking sheets with parchment. Preheat oven to 350°F midway through chilling. This setup prevents rushed mistakes and ensures smooth baking.

2-Second Step: Cream Butter and Sugar In a large bowl, beat 1 cup softened butter and ½ cup sugar with a mixer on medium speed until light and fluffy, about 2-3 minutes. Scrape sides often. This incorporates air for tender cookies. Avoid overbeating to keep dough from spreading too much.

3-Third Step: Add Egg Yolk and Vanilla Beat in 1 egg yolk and 1 tsp vanilla extract until combined, about 1 minute. Mixture looks glossy now. Egg yolk enriches dough; vanilla adds depth. Taste a tiny bit if needed, but cook fully later.

4-Fourth Step: Incorporate Flour Add 2 cups flour gradually, mixing on low speed until dough forms a soft ball. Do not overmix; stop when flour disappears. Dough feels smooth, not sticky. If too dry, add 1 tsp milk. Wrap in plastic and chill 1 hour. Chilling firms butter for clean cuts.

5-Fifth Step: Roll and Cut Dough Divide chilled dough in half. On floured surface, roll to ⅛-inch thick. Cut 3-inch rounds; half get small center cutouts (like 1-inch stars or circles). Re-roll scraps once. Place on sheets 2 inches apart. Prick solid rounds with fork to prevent puffing.

6-Sixth Step: Bake the Cookies Bake at 350°F for 10-12 minutes until edges turn golden. Centers stay pale. Rotate sheets halfway for even baking. Cool on sheets 5 minutes, then wire rack completely, about 1 hour. Full cooling prevents breakage and sogginess.

7-Seventh Step: Assemble the Sandwiches Spread 1 tsp room-temperature apricot jam on flat side of solid cookies. Top with cutout cookies, jam side down. Press gently. Chill assembled cookies 30 minutes to set if humid.

8-Final Step: Dust and Serve Sift powdered sugar over tops, filling cutouts for jewel effect. Serve immediately or store. Pair with tea or milk. These shine at parties.