Place ½ Tbsp of olive oil in a large cast iron skillet; place skillet over medium-high heat. Once hot, add the sliced sausage and cook until first side is browned (~5 minutes). Flip and cook for 5 more minutes. Transfer cooked sausage to a paper-towel lined plate; set aside. Once cool, slice each piece of sausage into 2 halfmoon pieces.

Drain all but ~1 Tbsp of grease from skillet; add diced onions and peppers. Stir and cook for 7-8 minutes, stirring occasionally, or until tender.

Preheat oven to 400°F.

Meanwhile, roll each sheet of thawed puff pastry into a 12”x12” square. Cut each sheet into (12) squares. (Note: each square will be ~3”x4”).

Lightly spray a mini-muffin tin with baking spray. Gently press one pastry square into each cup.

Fill each cup with 1-2 pieces of cooked sausage and ~1 Tbsp of cooked onions and peppers. Sprinkle tops with shredded cheese. Bring the 4 corners of the puff pastry together and pinch to seal.

Whisk together egg and 1 Tbsp of water; Brush closed tops of puff pastry with the egg wash. (Optional: Sprinkle tops of puff pastry with a pinch of dried oregano and sea salt.)

Bake at 400°F for 20-25 minutes, or until pastry is golden brown.