Add your chopped cauliflower to a large sheet pan and drizzle with 2 tbsp of your olive oil and mix well.
Season with a pinch of salt and roast your cauliflower in the oven for about 25-30 minutes or until nicely browned on edges. When done, remove from oven and set aside. It should be done just before your carbonara is ready so it will stay warm.
While your cauliflower is cooking, fill a pasta pot with water and bring to a boil for your pasta. I like to only fill my pot 3/4 of the way up to have extra starchy water from the pasta cooking. This will help your dish later!
While you wait for your pasta water to come to a boil, in a large saute pan, add your remaining 2 tbsp of olive oil and your pancetta and cook until the pancetta starts to lightly brown.
At this point add your garlic and saute for about 2-3 minutes making sure not to burn it.
Once your pancetta and garlic are finished cooking, remove them from the pan into a large bowl and set aside.
In a medium bowl, add your egg yolks along with a pinch of salt and a lot of freshly ground black pepper (1 tbsp).
Set aside for now.
Now, your pasta water should be boiling, salt it well and add your spaghetti stirring so it does not stick.
Cook until al dente according to the instructions on your pasta box.
Now take about 1/4 cup of that water out and bring it over to your egg yolk mixture.
Slowly whisk in that hot pasta water to lightly temper your egg yolks so they do not curdle later when added to your hot pasta.
Now, scoop out another 1/4 of your pasta water (in case you need it later) and drain your pasta.
Here is where you need to work fast!
Pour your hot pasta into your large bowl with the garlic and pancetta and quickly pour your egg mixture over the pasta and toss well.
Toss for a few seconds letting the pasta drink up the sauce.
Add 1/2 your Parmesan and toss again well.
Now assess if you carbonara looks dry. It should look creamy.
If the pasta seems too dry, add a little of that reserved pasta water and toss it again.
Plate into individual bowls with your pasta and top with your roasted cauliflower (that you set aside) and additional Parmesan and freshly ground black pepper.