PUFF PASTRY DOUGH: Follow package directions to thaw the dough. If using the Pepperidge Farms dough, there should be 2 sheets per package. Lightly flour a flat working surface. Unfold the two sheets of dough (do not roll it out or press it down) and place them on a lightly floured surface.
OIL: Pour oil into a deep fryer or heavy-bottomed deep pot (See Note 2). Use a candy thermometer to gauge heat or set the deep fryer to 350 degrees (it should beep or alert you with a light when it has reached temperature). It's very important to monitor the heat constantly -- too hot and the cronuts will be burned on the outside and raw/doughy inside and too cool they will end up overly chewy.
PREPARE AND CHILL DOUGH: Crack both eggs into a small bowl. Briskly whisk the eggs with a fork. Using a pastry brush, brush both of the puff pastry dough sheets with the egg wash (just one side). Then fold up each sheet of dough in thirds (like a letter and how you removed it from the packaging). Place in the freezer for 20 minutes.
CUT OUT DONUTS: Using donut or pastry cutters, cut out large cronuts. We use a 2-1/2 cutter to get 3 cronuts per sheet of puff pastry. Use a 1-1/2-inch cutter to cut out the center of each cronut. Repeat with the other sheet of puff pastry dough for a total of 6 cronuts and 6 donut holes. You can also save scraps of the dough and fry that up to avoid wasting the dough.
FRY: Place the doughnuts in the hot oil and fry for 5 minutes, flipping every 1 and 1/2 minutes with a fork, until each side has puffed up and is a nice golden brown, for a total of 5 minutes (make sure to monitor the heat and ensure it is constantly at 350 degrees F). Use a slotted spoon to remove the donuts from the oil and place on a plate lined with a few paper towels. Repeat until all the donut and donut holes have been fried.
CINNAMON SUGAR: Meanwhile, with a spoon, stir together the white sugar and cinnamon until combined. Using tongs or two forks (the donuts are hot straight out of the fryer), transfer the hot donuts from the paper towel-lined plate into this bowl. Gently spoon cinnamon sugar over the donuts and rotate with a fork until generously coated. Enjoy now or add a glaze (see next step).
GLAZE (OPTIONAL): Whisk together the glaze ingredients. If glaze is too thick, add more maple syrup (or milk) 1 teaspoon at a time. Microwave the glaze for 5-10 seconds or until thin enough for dipping. Gently dip the donuts into the glaze or drizzle over the donuts (sometimes the cinnamon sugar keeps the glaze from adhering as nicely). Let set for a minute and then enjoy! Cronuts are best enjoyed hot and fresh out of the fryer after being coated in sugar and/or glazed!