Add the butter and powdered sugar to the mixing bowl with the paddle attachment. This can also be done with a hand mixer or by hand. Mix for about 1 minute to combine. Add in vanilla and mix for just a few seconds.
I like this to be a one-bowl mix. To do this, add your flours over the butter mixture. Add the salt directly on top of the flours. With a spoon, mix the salt into the flours, just on top. With the salt mixed in, you can now mix it in with the butter mix. Mix this only to combine.
The dough will need to be chilled before going further. Scrape it from the bowl and wrap it in saran wrap. Chill for at least one hour.
Preheat the oven to 350 degrees.
Line 2 baking sheets with parchment paper, and set aside.
I rolled my cookie dough between parchment paper. If you don't want to do this, lightly flour your surface and roll there.
Roll your cookies about ¼ inch thick. You can roll them thicker than this, but I like this thickness.
Cut with your cookie cutter, and carefully move to the parchment-lined baking sheet. If the dough has softened too much and you rolled it on parchment, place it in the freezer for about 5 minutes, then it will be simple to move
Once the cookies are cut, place your edible flowers on top. Pressing the flowers once placed with a sheet of parchment or your fingers.
Bake until the edges are a very, very light brown. I don't like hardly any color on my shortbread.
Once the cookies are baked, sprinkle immediately with granulated sugar. Allow them to cool slightly before eating.