Combine butter and sugar in bowl of stand mixer and cream* until fluffy and nearly white in color.
Add egg and combine slowly until uniform.
Add flour in three equal parts, mixing in each addition just until combined.
Remove dough from mixer and chill for 1 hour.
Preheat oven to 350°F.
Lightly flour work surface and roll chilled dough to ½-inch thick.
Cut out Demiguise shape using template provided below.
Transfer each cookie to parchment-lined baking sheet. Press blue candies into cookies for eyes.
Chill cookies for 10 minutes.
Bake cookies for 10 minutes, or until lightly golden brown and firm to touch.
Allow to cool completely.
Frost with prepared royal icing to mimic Demiguise fur, as desired. Allow to dry.