Check out the rest of Katherin's gorgeous work on her Facebook page, HERE!
Follow Katherine on instagram! @katssweetthings

Click HERE to see the royal icing recipe she uses (though she notes that she adds the vanilla extract after adding the sugar and then lets it combine.)
Katherine's favorite tools:

Joseph Joseph rolling pin Linsnfield
heat sealer
Genies Dream Meringue Powder
Tipless bags from Grunderfully Delicious or Truly Mad Plastics
Pico projector
scribe tool

And her are a few of her favorite cookie cutter designers:

Kaleida Kuts
Sweetleigh Printed
The Sweet Designs Shoppe

The cookie recipe that Katherine uses:
Yield
2 dozen - 4" cookies
Yield amount
2 minutes
Yield units
dozen - 4" cookies
Ingredients
4 cupsAll Purpose Flour(480 grams - preferably sifted)
1 teaspoonBaking Powder(4 grams)
1⁄2 teaspoonSalt(2.9 grams)
8 ouncesUnsalted Butter(227 grams (2 american sticks) - softened)
2 cupsGranulated Sugar(396 grams)
2Whole Eggs(large)
2 teaspoonsVanilla Extract(9.9 ml)
2 gramsabc(abc note)
Instructions

Sift flour, baking powder, and salt into a bowl. In a separate bowl, beat butter and sugar with a mixer on medium speed until pale and fluffy, about 3 minutes. Beat in eggs and vanilla. Reduce speed to low. Gradually mix in flour mixture. Turn out dough, and divide in half. Flatten each half into a disk, and wrap in plastic. Refrigerate until firm, at least 1 hour or overnight.
Preheat oven to 325 Fahrenheit (163 Celsius), with racks in upper and lower thirds of oven. Let one disk of dough stand at room temperature just until soft enough to roll, about 10 minutes. Roll out dough on a lightly floured work surface to just under 1/4-inch thick, adding more flour as needed to keep dough from sticking. Chill in refrigerator until firm, about 30 minutes. Cut out cookies using desired cutters or templates. Transfer to parchment-lined baking sheets as you work. Roll out scraps, and repeat once. Repeat with remaining disk of dough. Chill cookies in freezer until very firm, about 15 minutes.
Bake cookies, switching positions of sheets and rotating halfway through, until edges turn golden, 15 to 18 minutes. Let cool on sheets or wire racks. Decorate with Royal Icing.

https://www.marthastewart.com/354971/sugar-cookies