Preheat oven to 160 degrees C / 320 degrees F if making the roasted garlic.
Using a sharp knife, slice the top off the garlic bulb, about 2 – 3 cm down from the top to expose the raw cloves. Place the bulb of garlic into the centre of an oven proof dish, drizzle with olive oil and season with salt and pepper. Bake for 1 hour.
Allow the garlic to slightly cool until you are able to handle it. Using your fingers, squeeze the roasted garlic cloves out of their skin. Set to the side.
Turn the ovens temperature to 180 degrees C / 350 degrees F
Bring a large pot of heavily salted water to the boil. Follow the instructions on the back of the pasta packet for al dente pasta and drain your pasta 2 minutes before the suggested cooking time. Stir through a teaspoon of butter through the drained pasta and leave to slightly cool.
In an oven proof pot on a medium heat, combine the butter and olive oil and cook until melted. Add the flour and garlic to the pan and whisk to form a roux. Stir constantly for 1 – 2 minutes.
Add the milk to the roux, one cup at a time and whisk until combined and lump free. Repeat this step 2 more times until you have used up all the milk. Whisk the sauce for 5 minutes or until slightly thickened.
Take off the heat and stir through the cheese with a big pinch of salt and pepper. Season to taste.
Add the pasta to the sauce and stir through. Sprinkle the remaining cheese all over and bake for 15 minutes or until golden on top. Serve immediately.