Fry the bacon pieces in 15g (1 tbsp) butter until golden and crisp, set aside.
In a large fry pan or casserole dish melt the other 15g (1 tbsp) of butter and 1 tbsp olive oil over medium heat and gently cook the onion for 3 mins until softened. Don't let it catch on the bottom.
Add the garlic and cook for a further 2 minutes.
Add the rice and cook for a couple of minutes, stirring until translucent and coated.
Add the red wine and let it absorb, stirring. You don't want a fierce boil or bubble ever, just a gentle simmer the whole time.
Once the wine is mostly absorbed start adding a ladle of stock, one at a time, letting it absorb between each addition.
You really need to be stirring the whole time, it can't catch on the bottom. By stirring constantly you are rubbing the starch into the liquid making it creamy and delicious.
After 20 mins it will be almost done, at this point add the bacon and rosemary.
Add one or more two ladles, you be the judge. The grains should have become much plumper but you want to make sure they retain a slight bite. You don't want it all soft and sludgy.
Add the 20g of butter and the parmesan and stir to melt.
I like to add ½ a ladle right before I take it off the heat so by the time I serve it on plates it's the perfect consistency. The rice will keep soaking up the liquid even off the heat so make sure there is enough liquid so it's not super stiff on the plates.
Serve with extra parmesan on top and a little drizzle of olive oil round the edge is nice too!