Pre-heat oven to 400 degrees.
Peel away the outer layers of garlic skin, making sure the cloves remain intact. Cut about ¼ inch off the top of each head, so the cloves are exposed. Place heads of garlic in a muffin tin.
Drizzle some olive oil over the tops, making sure it’s rubbed into the cloves. And then wrap the tops with aluminum foil.
Bake for 30-35 minutes, until the cloves get soft and are very fragrant. Remove garlic from oven, but keep oven on for mac and cheese.
Once the garlic has cooled enough that you can touch it, pull the cloves out of the skin. Place cloves in a bowl and mash them with a fork. Set aside.
Bring a large pot of salted water to a boil. Add pasta and boil until al dente. Drain pasta and keep pasta in colander so you can use pot for the cheese sauce.
While pasta is boiling, cook sausage in a medium skillet over medium heat until it's cooked through. Remove from skillet to small bowl and set aside.
Melt butter in the pot you cooked the pasta in over medium heat. Once melted, pour 2 Tbsp into a small bowl and set aside (this will be for the panko topping).
Add flour and mustard powder to the remaining melted butter in the pot and whisk for a minute, without letting the flour darken. Whisk in milk and bring the mixture just to a boil, before reducing heat to medium-low and letting simmer for 2-3 minutes while sauce thickens.
Remove saucepan from the heat and whisk in both cheeses and the smashed roasted garlic. Sprinkle with ¼ tsp salt and ¼ tsp pepper.
Pour cheese sauce over cooked pasta in pot. Mix in sausage and kale.
Put pasta mixture into a 9x11 baking dish.
Add panko and ¼ tsp sat to the bowl with the reserved butte and stir together. Evenly sprinkle over mac and cheese.
Place in pre-heated oven for about 15-20 minutes, until the panko browns and gets crispy. Remove from oven and serve hot.