1/2teaspoonrosewater, Rosewater concentration may vary depending on the brand. I would highly recommend to taste as you go, to make sure you have the perfect balance of rosewater in your glaze. You don't want your cookies to taste like soap!
Decoration
Crushed pistachios
Dried rose petals
White chocolate shavings
Coarse sanding sugar
Lavender mocha butter cookies
1large egg, hard-boiled and cooled
10tablespoons(140 grams or 1/2 cup and 1 tbsp) unsalted butter, softened
Place butter, sugar and salt in the bowl of stand mixer with the paddle attachment. Crack egg and peel shell. Separate yolk from white and set aside the egg white (you don't need it anymore). Press yolk through fine-mesh strainer and into mixer bowl with other ingredients. Beat mixture on medium speed until light and fluffy, scraping down sides of bowl and beater with spatula as needed. If you are making the rosewater variation, add the rosewater at this stage and mix until combined.
Add flour and mix at low speed until just combined. If you are making the mocha variation, whisk the cocoa powder and instant espresso powder with the flour before adding it to the butter mixture. If dough is slightly crumbly, use a rubber spatula or your hands to knead a few times and to combine the dough.
Place a piece of parchment paper on a flat surface, place dough on parchment, and place another piece of parchment on top. Using a rolling pin, roll our the dough into 1/4 inch thickness. Using a cookie cutter of your choice, cut out the shapes and place cookies onto a baking sheet lined with parchment paper. Chill unbaked cookies for roughly 30 minutes before baking.
While dough is chilling, preheat oven to 350 degrees.
Bake cookies until they have golden brown edges, about 13 to 15 minutes. Remove from oven but let firm up on baking sheet for 5-10 minutes before transferring cookies to cooling racks.
Make glaze, dip cookies, and decorate away. Dip the cookies in the glaze as you go along. Don't dip them all at once before decorating them because the glaze might set before you get to some of the cookies. Let glaze on cookies harden for about an hour before stacking/storing the cookies.