Heat a drizzle of olive oil in an oven-safe pan over medium heat. Add the ground meat (sausage or beef) and brown it, breaking it up as it cooks. Once browned, remove the meat from the pan and set it aside.
In the same pan, add a tablespoon of butter and the chopped leek, onion, and garlic. Sauté for about 5 minutes until the vegetables are soft and translucent. Season with salt, pepper, and Italian seasoning.
Add the can of crushed tomatoes to the pan and bring it to a simmer. Add the browned meat back into the pan, stirring to combine. Let it bubble away for about 20 minutes, stirring occasionally, to allow the flavours to meld.
While the sauce is simmering, preheat your oven to 350°F (175°C).
Cook the tortellini until it just floats to the top and then add directly to the meat sauce. Then, stir in the chopped kale until wilted.
Top the mixture with torn burrata and transfer the pan to the oven. Bake for 15 minutes until bubbly, then turn on the broiler for the final 2-3 minutes to get a golden, crispy top.
Serve: Remove from the oven and let it cool for a few minutes before serving. I like serving with crushed red pepper flakes on top for a bit of a kick (optional). Enjoy!