Preheat oven to 350 F degrees. Prepare the baking sheets by lining them with parchment paper or silicone baking mats.

In a bowl, sift together the flour, baking soda and salt. Use a wire whisk and whisk the powdered ingredients around a couple of times.

Separately, using a stand mixer with the paddle attachment, beat together the butter, sugar, vanilla sugar and vanilla extract on medium speed till light and fluffy, for 2 minutes.

Add the egg white and oil. Continue beating until batter is smooth, about 1 minute more.

Reduce the mixer speed to low and slowly add the dry ingredients. Mix till the batter is smooth.

Turn the dough out on a large sheet of parchment paper and pat it into a disk.  Using a rolling pin, roll out the dough to ¼ inch thick. Place sheets of parchment between the dough. Transfer to a third baking sheet or a flat plastic container. Freeze until firm, for at least 10 minutes. Or if you prefer, cover the cookie dough in plastic wrap, then place in an air tight container and freeze at least 6 hours or overnight.

When ready to bake, cut the dough with a round cookie cutter, measuring 1 and ½ inch in diameter. Roll the cookie dough in colored sugar sprinkles.  Place them an inch apart on the prepared baking sheets. Bake 15 to 18 minutes at in a preheated oven of 350 F degrees.

When done, cool the cookies for a minute on the tray, then transfer them to a cookie rack to cool completely.

RECIPE NOTES: To make Homemade Vanilla Sugar, the cookbook 'Pure Vanilla" suggested to place 1 or 2 vanilla bean pods inside a jar of granulated sugar. I placed my vanilla bean in an 8 ounce jar filled with 1 to 2 cups of sugar and let it sit for at least 2 days before using as a baking ingredient.