Preheat oven to 400F. Dice onion and add to sauté pan with olive oil, garlic powder, red pepper flakes, and salt over medium heat. Cook until glossy and soft.
Add sausage to the pan with cooked onions.
Cook sausage until browned.
Transfer onions and sausage to a plate lined with paper towels to drain the excess fat.
Combine cooked sausage with minced parsley and toss together.
Roll out the puff pastry sheet and cut into 6 squares. Transfer to parchment-lined baking sheet.
Divide the sausage mix among the 6 squares.
Divide the shredded cheddar cheese among the 6 sections of puff pastry.
Pinch them closed by joining corners until they are fully closed.
Brush each with milk and bake for 20-23 minutes. You can place a square of tinfoil on top of each pie, if needed, to keep them from burning.
*This recipe works with everything from ground hot Italian sausage to ground sweet maple breakfast sausage. Just choose your sausage based on what's least expensive at the grocery store or when you're planning to serve them. If you choose a spicy ground sausage, you can omit the crushed red pepper flakes. I used a breakfast sausage, so I added the kick of pepper!This was done in 23 minutes in our convection oven at 400F. If yours takes more or less time, that's okay, when the puff pastry looks golden brown, it's done!