Preheat your oven to 400°F (200°C). Gather your ingredients while the oven heats.

Grease a 9x13-inch baking dish. Layer the thinly sliced russet potatoes in the bottom.

Spread the cooked and crumbled Italian sausage over the potatoes, then add the crispy bacon bits.

Heat reserved bacon grease in a skillet; sauté chopped onion and garlic paste for 2-3 minutes.

Stir in chopped kale and cook until wilted, about 2-3 minutes.

Sprinkle flour over the kale mixture and stir well for about a minute.

Gradually whisk in chicken broth, stirring until the mixture thickens slightly.

Stir in heavy whipping cream until smooth.

Beat the egg, temper it with hot liquid from the skillet, then whisk it back into the sauce.

Mix in half of the Parmesan cheese until melted and creamy.

Pour the creamy sauce evenly over the layered potatoes and meat, then cover with foil.

Bake for 50-60 minutes until potatoes are tender, then remove foil and add remaining cheese.

Bake for an additional 25-30 minutes until cheese is golden and bubbly. Let rest for 10 minutes before serving.