We found that Jolly Rancher candies produced the brightest, most vibrant "stained glass." Be sure to use the original sweet candies, not the sour flavors. To crush, place each color in its own heavy-duty zip-top bag; crush with a rolling pin or meat mallet. You'll find sparkling sugar in craft or specialty stores, but you can also use turbinado sugar as a substitute.
4 ounces white whole-wheat flour (about 1 scant cup)
4 ounces all-purpose flour (about 1 scant cup)
1/4 teaspoon salt
1/2 cup unsalted butter, softened
2/3 cup granulated sugar
1 teaspoon vanilla extract
1 large egg
8 hard candies (such as Original Jolly Rancher, 2 each of 4 colors)
1 tablespoon 2% reduced-fat milk
2 tablespoons sparkling sugar
How to Make It
Weigh or lightly spoon flours into dry measuring cups; level with a knife. Combine flours and salt in a bowl, stirring with a whisk.
Place butter and granulated sugar in a large bowl. Beat with a mixer at medium speed until light and fluffy (about 4 minutes). Add vanilla and egg; beat 1 minute or until completely combined. Add flour mixture; beat just until combined. Scrape dough onto a work surface; shape into a 7-inch disk. Wrap dough in plastic wrap. Chill 45 minutes.
Preheat oven to 325°.
Crush candies, keeping colors separate and placing each color in a small bowl.
Place dough disk on a lightly floured work surface; roll dough to 1/4-inch thickness. Cut cookies using a 2 1/2-inch cookie cutter dusted with flour. Cut out center of each cookie with a 1-inch cookie cutter to make 24 cookies; discard scraps. Place cookies on 2 baking sheets lined with parchment paper. Fill the cutout centers of cookies with crushed candies.
Lightly brush edges of cookies with milk. Sprinkle tops with sparkling sugar. Bake at 325° for 12 to 13 minutes or until edges are golden brown. Cool cookies completely before removing from pans.
Bake a Second Batch The dough is easily doubled; just divide into two disks, and chill separately. Roll out and cut one at a time. Be sure to cool the cookies completely on the pan before moving them so the candy centers firm up.