In the bowl of a stand mixer, beat together cream cheese and butter until smooth. Add sugar and vanilla and mix to incorporate fully.
In a medium bowl, whisk together flour and salt. Slowly add the flour to the butter mixture until it forms a dough that begins to pull away from the sides of the bowl. {*I usually add just 2 cups of flour and then sprinkle in an extra ¼ to ½ cup while the mixer goes until the dough is no longer super sticky.} Try not to over mix.
Turn out dough onto a lightly floured surface and, with floured hands, gently knead it together to form a ball -- divide it in half. Place each half on a sheet of plastic wrap. Pat dough into 2 square-ish shapes and wrap well. Refrigerate until the dough is firm, several hours or overnight.**
When the dough is firm, place one square onto a lightly floured surface and roll out to a rectangle or square, about ¼ inch thick. Using a pizza cutter or sharp knife, cut as many 2 inch-wide strips across as you are able to, then repeat vertically to end up with 2x2 inch squares of dough. If you have scraps left over, re-roll the scraps and repeat the process.
Place the dough squares on a baking pan -- the corners should be facing each other so that you have a tray full of "diamond" shapes. Preheat the oven to 375°F degrees.
Fill a zip top plastic bag or small piping bag with chocolate hazelnut spread, then snip the tip. Pipe a straight line down the center of each diamond from tip to tip -- I estimate I used about a teaspoon of spread in each cookie. Sprinkle each cookie with chopped hazelnuts, pressing lightly to adhere to the spread.
Wet your fingertips with a little bit of water and lightly swab one side of the cookie dough to moisten -- this will make it slightly sticky so that it adheres to the other side and stays closed. Carefully fold the outer edges of the diamond in toward the center {like it's hugging itself}, making sure to fold the sticky side over the non-sticky side so that it helps to seal the cookie. Repeat until all cookies are sealed into bow ties.
Bake for about 12 minutes until they're just slightly golden at the edges. They'll be a little soft when you take them out of the oven, but they'll firm up slightly. Remove from baking pan and place on a cooling rack.
Once cooled, sprinkle with powdered sugar before serving.