Preheat Oven and Prepare Baking Sheet: Preheat oven to 350°F (175°C). Line a small to medium-sized baking sheet with parchment paper. Set aside.

Make Sausage Gravy: In a large skillet (cast iron recommended) over medium-high heat, cook the ground sausage until browned and cooked through, breaking it up with a spoon or spatula. Do not drain the grease. Reduce the heat to medium-low. Sprinkle the flour over the sausage and grease in the skillet. Stir constantly until the flour is fully incorporated and forms a roux (a paste). Cook for 1-2 minutes, stirring constantly, to cook out the raw flour taste. Gradually whisk in 1/4 cup of milk and the pepper. The mixture should bubble. If the gravy is too thick, add more milk, 1 tablespoon at a time, until it reaches your desired consistency. For these bars, a thicker, drier gravy is preferred. Remove the skillet from the heat and set aside. (If you plan to reuse the skillet for the remaining steps, transfer the gravy to a bowl and clean the skillet.)

Cook Bacon: Cook the bacon to your desired crispness using your preferred method (air fryer, stovetop, oven, or microwave). Once cooked, crumble the bacon and set it aside.

Cook Hash Browns: In a skillet (you can use the same one, cleaned, if you transferred the gravy), cook the frozen shredded hash browns according to package directions, or until golden brown and crispy on both sides. If using oil, use a small amount of olive oil and add it only as needed to prevent sticking. Avoid making the hash browns too greasy.

Prepare Egg Wash: In a small bowl, whisk together the egg and heavy cream until well combined.

Assemble Bars:

• Unfold one sheet of thawed puff pastry and place it on the prepared baking sheet.
• Spread the sausage gravy evenly over the puff pastry, leaving about a 1-inch border of bare pastry around the edges.
• Layer the cooked hash browns evenly over the sausage gravy.
• Carefully pour about half of the egg mixture over the hash browns. Try to distribute it evenly, and avoid letting large amounts of the egg mixture spill onto the bare pastry border.
• Brush the bare pastry border with some of the remaining egg wash.
• Layer the 4 slices of Havarti or cheddar cheese over the egg mixture.
• Sprinkle the crumbled cooked bacon evenly over the cheese.
• Sprinkle the 1/2 cup of shredded cheddar cheese over the bacon.
• Carefully place the second sheet of thawed puff pastry over the filling.

Seal and Crimp Edges: Gently press the edges of the top and bottom puff pastry sheets together to seal them. Use the tines of a fork to crimp the edges all the way around, creating a decorative and secure seal.

Egg Wash Top: Brush the top of the assembled pastry with the remaining egg wash.

Bake: Bake for 18-23 minutes, or until the puff pastry is golden brown and cooked through.

Cool and Serve: Let the baked pastry cool for 5-10 minutes before cutting it into 9 (or smaller) pieces. Serve warm for the best flakiness and flavor.