Once the dough is done chilling, roll it out on a lightly floured surface into a long rectangle about 15x5 inches.
Cut the long rectangle in two across the width.
Starting with the first half of the dough, cut the rectangle across the width into five equal sections, and those five sections vertically down the middle, creating ten small rectangles.
Cut each of those small rectangles diagonally, creating 20 very small triangles. Repeat with the second half of the dough. At this point, I recommend placing all of the triangles on a baking sheet lined with parchment paper and chilling them in the fridge or freezer for 10-15 minutes.
While the triangles chill, preheat the oven to 375 degrees F.
Take a few triangles out and spread the cinnamon sugar filling onto them, then roll them up as you would with traditional croissants. Place them back on the baking sheet in the fridge or freezer, and take a few more out. This is not only the best way to ensure that the dough remains cold, but it also makes the dough much easier to work with.
Once all of the mini croissants are shaped, freeze them for about 15-20 minutes.
Brush the mini croissants with an egg wash and bake at 375 degrees for 12-16 minutes until golden.
Roll them in cinnamon sugar and enjoy!