Preheat the oven to 350°F (175°C).
Line a baking sheet (or multiple baking sheets) with parchment paper. Arrange the 24 slices of provolone cheese on the baking sheet(s), leaving space between each slice.
In a small bowl, mix together the cooked ground Italian sausage, cream cheese, sour cream, and shredded mozzarella cheese. Set aside.
Place the baking sheet in the oven for 3 minutes, or until the cheese starts to bubble and turn golden brown around the edges. Remove the baking sheet from the oven and let the cheese cool for 3-5 minutes.
Add a scoop of the Italian sausage filling to the center of 12 cheese slices. Place the remaining 12 slices of melted provolone on top, gently lifting with a spatula.
Press down around the edges of the provolone cheese to seal the ravioli.
Turn the oven to broil and return the baking sheet to the oven. Broil for about 30 seconds, just enough to heat the top slice and ensure the edges are sealed.
Remove the ravioli from the oven and let them cool for a few minutes before plating. Serve with your favorite keto marinara sauce and a sprinkle of parmesan or pecorino romano cheese. Enjoy!