Preheat oven to 425˚F/220˚C. Line a sheet pan with parchment paper.
Coat cauliflower in oil and seasonings then spread the pieces into one layer on the sheet pan.
Roast cauliflower for 30 minutes turning halfway through cooking.
Meanwhile, bring a large pot of water to a boil before salting it with a few tablespoons of kosher salt.
Cook the pasta in boiling salted water until al dente according to the package. Drain and set aside.
Grate 20 oz. of the cheese and cut the remaining 4 oz. into small cubes.
Heat an enameled dutch oven or heavy-bottomed pot on medium then add the butter and olive oil.
Once the butter has melted add the flour and stir constantly for about 5 minutes to cook the flour and make a roux.
Then stir in the yogurt followed by the seasonings. Continue stirring until the sauce just starts to bubble. Be careful not to let the sauce boil or it could split.
Stir in the grated cheese, reserving about 1 cup to use alter. Keep stirring until the sauce is smooth and creamy and coats the back of a spoon.
Remove from the heat and stir in the cooked pasta and cauliflower.
Add half of the mac and cheese to a baking dish then dot the top with the cubed cheese. Cover with the rest of the mac and cheese and top with the reserved grated cheese.
Broil the mac and cheese for about 5 minutes to melt the cheese and form a nice golden brown crust.
Serve hot and enjoy. Leftover mac and cheese with keep covered and refrigerated for up to 3 days. Reheat to serv